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0000-0002-7991-4117
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Bond University Faculty of Health Sciences and Medicine
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Publisher: Wiley
Date: 10-02-2001
DOI: 10.1046/J.1365-2680.2001.00200.X
Abstract: 1. The present study investigates the effect of short-term experimental diabetes of 14-days duration on the beta-adrenoceptor subtypes of the rat heart. 2 .beta-adrenoceptor-mediated functional responses to submaximal doses of isoprenaline were enhanced in Langendorff-perfused hearts from diabetic rats, manifested as greater changes in tension, heart rate and rates of tension development (+dT/dt) and decline (-dT/dt). 3. Radioligand binding data demonstrated that total cardiac beta-adrenoceptor density and affinity for [3H]-dihydroalprenolol was unchanged by diabetes, although a decrease in beta1-adrenoceptor density and increase in beta2-adrenoceptor density was observed. 4. In conclusion, hearts from 14-day streptozotocin-induced diabetic rats demonstrate a number of alterations within the beta-adrenoceptor system. However, the enhanced beta-adrenoceptor-mediated responses to isoprenaline were not caused by an overall increase in density of beta-adrenoceptors, but were accompanied by changes in the ratio of the beta-adrenoceptor subtypes.
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.TIV.2013.04.015
Abstract: The effects of pseudomonal virulence factor pyocyanin, and LPS from Pseudomonas aeruginosa and Escherichia coli on urothelial mediator release and cytokine production were examined. RT4 urothelial cells were treated with pyocyanin (1-100 μM) or LPS (1-100 ng/mL) for 24-h. Effects were measured in terms of changes in cell viability, basal and stretch-induced acetylcholine (Ach) and PGE2 release, and inflammatory cytokines (IL-6 and IL-12) production. Twenty-four hour pyocyanin (100 μM) treatment significantly decreased urothelial cell viability, while stretch-induced Ach release response was inhibited. E. coli LPS (100 ng/mL) produced a similar response with an additional significant increase in basal Ach release. All three virulence factors significantly increased urothelial PGE2 release under basal release for pyocyanin (100 μM), stretch-induced release for pseudomonal LPS (≥ 10 ng/mL) and both basal and stimulated release for E. coli LPS (≥ 10 ng/mL). IL-6 and IL-12 were not detected in control s les, however 24h treatment with pyocyanin (100 μM) or LPS (100 ng/mL) resulted in IL-6 release from urothelial cells. The changes in urothelial Ach and PGE2, and release of inflammatory cytokine IL-6 induced by exposure to the bacterial virulence factors may play a role in the symptoms of pain and urinary urgency experienced with urinary tract infections.
Publisher: Wiley
Date: 08-1992
DOI: 10.1111/J.1474-8673.1992.TB00334.X
Abstract: 1. The effects on cardiac responsiveness of diabetes of up to 12 weeks duration has been examined in streptozotocin-pretreated rats. 2. Two weeks of diabetes resulted in a supersensitivity of isolated left atria and papillary muscles to isoprenaline, which was associated with an increase in the density of ventricular [3H]-dihydroalprenolol binding sites. 3. The beta-adrenoceptor supersensitivity was still evident in both tissues after 4 weeks of diabetes, but in left atria the supersensitivity was reduced compared with that observed at 2 weeks, while for papillary muscles it was greater than at 2 weeks. 4. Following 12 weeks of diabetes, responses of papillary muscles to isoprenaline were similar to controls, while beta-mediated responses of left atria were significantly depressed. 5. The alpha-adrenoceptor-mediated responses of cardiac tissues to phenylephrine were similar to controls following diabetes of 2 or 4 weeks duration. At 12 weeks, however, papillary muscle alpha-adrenoceptor-mediated responses were enhanced. The change in ventricular responsiveness to phenylephrine was not accompanied by any change in [3H]-prazosin binding to ventricular membranes. 6. The results demonstrate a transient elevation of cardiac beta-adrenoceptor sensitivity and receptor density during acute diabetes and illustrate the time- and tissue-dependence of diabetes-induced changes in cardiac adrenoceptor sensitivity.
Publisher: Elsevier BV
Date: 08-2007
DOI: 10.1016/J.EURURO.2006.11.016
Abstract: This study examines whether M(2) receptors contribute to direct contraction of the detrusor in human neurogenic and idiopathic overactive bladders. Control detrusor muscle was obtained from patients undergoing cystectomy for bladder cancer, whilst overactive detrusor muscle was obtained from patients undergoing clam cystoplasty for idiopathic or neurogenic detrusor overactivity. The affinities of a range of subtype selective antagonists (DAMP, darifenacin, methoctramine R0-320-6206, and pirenzepine) were obtained in tissue bath experiments by using carbachol as the agonist. These affinity values were then compared with the known affinities for these antagonists at the muscarinic receptor subtypes. An increased sensitivity to carbachol was observed in both the neurogenic and idiopathic overactive detrusors compared with the control human detrusor. The M(2)-selective antagonists (methoctramine, R0-320-6206) and M(1)-selective antagonist (pirenzepine) had low affinities, whilst the M(3)-selective antagonists (4-DAMP and darifenacin) had high affinities for the human detrusor muscarinic receptor in all three groups of tissues. The affinities (pK(B) values) for the five antagonists were consistent with antagonisms at the M(3) receptor in all three groups Schild plot analysis indicated an action at this single receptor subtype. Contraction mediated by muscarinic receptors is enhanced in idiopathic and neurogenic overactive detrusors compared with control detrusor. The direct contractile response to carbachol is mediated by the M(3) receptor in both human normal and overactive bladders, indicating no change in receptor subtype contribution to contraction in the disease state.
Publisher: Wiley
Date: 04-2008
DOI: 10.1038/BJP.2008.29
Publisher: Wiley
Date: 30-08-2007
Publisher: Elsevier BV
Date: 09-1984
DOI: 10.1016/0024-3205(84)90074-2
Abstract: Positive inotropic and chronotropic responses of guinea-pig isolated left and right atria to sympathomimetic amines were examined at bath temperatures of 38, 30 or 25 degrees C. The concentration-response curves to isoproterenol and orciprenaline were displaced to the left by cooling, indicating hypothermia-induced supersensitivity. The affinities of isoproterenol and orciprenaline were determined as their dissociation constants (pKA) from antagonism of their responses by either the functional antagonist carbachol or Ro 03-7894 which is reported to be an irreversible beta-adrenoceptor antagonist. By both methods of calculation, the affinities of isoproterenol and orciprenaline for the beta-adrenoceptors mediating inotropic and chronotropic responses were increased by lowering the temperature. In contrast, the affinity of practolol, measured as the pA2 for competitive antagonism of the isoproterenol- and orciprenaline-induced inotropic and chronotropic responses, did not increase with cooling. Thus hypothermia-induced supersensitivity is associated with an increase in agonist affinity only, which indicates a fundamental temperature-dependent difference between agonist and antagonist interactions with the beta-adrenoceptor.
Publisher: Elsevier BV
Date: 09-1987
DOI: 10.1016/0160-5402(87)90003-9
Abstract: The object of this study was to determine suitable experimental conditions for the pharmacological evaluation of cardiac alpha-adrenoceptors. Atrial and ventricular preparations of the guinea pig and rat were employed, and the alpha-adrenoceptor responsiveness was compared with the binding of the alpha-adrenoceptor radioligand [3H]prazosin in membranes prepared from these cardiac regions. The experimental variables examined were the pacing frequency, bath temperature, choice of agonist, and cardiac region. In guinea pig atria the optimum alpha-adrenoceptor-mediated positive inotropic response to phenylephrine was at 32 degrees C and a pacing frequency of 1 Hz. A comparison of phenylephrine with methoxamine showed that the former yielded biphasic concentration-response curves in guinea pig left atria the lower portion was alpha-adrenoceptor mediated and the upper, more substantial portion, was beta mediated. Methoxamine produced monophasic curves due entirely to alpha-adrenoceptor stimulation and was therefore used for comparisons between rat and guinea pig tissues. Of the guinea pig tissues, only the left atrium produced positive inotropic responses. Negative chronotropy was obtained with right atria and negative inotropy with ventricular strips and papillary muscles. The rat tissues all responded with positive responses, the largest maximum being in the left atrium. Binding data showed a larger number of alpha-adrenoceptors in the rat tissues, of which the ventricles had the greatest number. The lack of response of guinea pig ventricular tissues was therefore reflected in the low binding. From this study, the most appropriate model for characterizing cardiac alpha-adrenoceptors is therefore the rat left atria at 32 degrees C and paced at 1 Hz with methoxamine as the agonist.
Publisher: Wiley
Date: 26-09-2012
DOI: 10.1111/AAP.12000
Abstract: Acetylcholine, and to a lesser extent ATP, mediates neurogenic contractions of bladder smooth muscle. Recently, the urothelium and lamina propria have also been shown to have contractile properties, but the neurotransmitters involved in mediating responses to nerve stimulation have not been investigated. Isolated strips of porcine urothelium with lamina propria were electrically field stimulated and contractions recorded. Drugs interfering with neurotransmission were then employed to identify which neurotransmitters mediated responses. Strips of urothelium/lamina propria developed spontaneous contractions with a frequency of 3.5±0.1 cycles min⁻¹ and litude of 0.84±0.06 g. Electrical field stimulation at 5, 10, and 20 Hz resulted in frequency-related contractions (1.13±0.36 g, 1.59±0.46 g and 2.20±0.53 g, respectively, n=13), and these were reduced in the presence of tetrodotoxin (1 μm) by 77±20% at 5 Hz, 79±7% at 10 Hz and 74±12% at 20 Hz (all P<0.01), indicating they were predominantly neurogenic in nature. Neither the muscarinic antagonist atropine (10 μm), the adrenergic neurone blocker guanethidine (10 μm) nor desensitization of the purinergic receptors with α,β-methylene ATP (10 μm) affected the contractile litude. Similarly, responses were not affected by the nitric oxide synthase inhibitor L-NNA (100 μm) or drugs that interfere with peptide neurotransmission (capsaicin, NK2 antagonist GR159897, protease inhibitors). In conclusion, electrical depolarization of the nerves present in the porcine urothelium/lamina propria results in frequency-dependent contractions, which are predominantly neurogenic in nature. These contractions are resistant to drugs that inhibit the adrenergic, cholinergic and purinergic systems. The neurotransmitter involved in the responses of this tissue is therefore unknown but does not appear to be a peptide.
Publisher: MDPI AG
Date: 09-08-2016
Publisher: Wiley
Date: 26-06-2020
DOI: 10.1111/PCMR.12903
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2004
DOI: 10.1097/01.JU.0000131244.67160.F4ABSTRACT
Abstract: Although the sensory and motor roles of the purinergic system in the bladder are well proven in animal species, there is increasing evidence that it may have an important role in humans. In addition, it may be important in the pathophysiology of bladder dysfunction. We established the level of adenosine triphosphate (ATP) release from porcine and normal human bladders. Bladder strips from patients with a urodynamically proven stable bladder undergoing surgery for stress incontinence and those undergoing cystectomy for cancer with no lower urinary tract symptoms were subjected to varying degrees of stretch (up to 50%) and electric field stimulation (10 to 40 Hz). A luciferase assay was used to quantify ATP release. Significantly increased ATP release over baseline was induced by mechanical and electrical stimulation (each p <0.05). Mean ATP release +/- SE from porcine bladders (38.2 +/- 1.9 pM/gm tissue following stretch and 19.9 +/- 6.5 pM/gm following electrical stimulation) was comparable to the release from human bladders (26.1 +/- 2.4 pM/gm tissue following stretch and 29.9 +/- 1.0 pM/gm following electrical stimulation). The main source of ATP release was the urothelium and not the muscle (p <0.05). This ATP release following stretch was not tetrodotoxin sensitive. The characteristics of ATP release from porcine and human bladders are similar and, therefore, the pig is a good model for humans. The main source of ATP release is urothelium from predominantly nonneuronal sources. This study supports a sensory role for ATP. An increased role for this purinergic neurotransmission may result in functional motor as well as sensory bladder disorders.
Publisher: S. Karger AG
Date: 2018
DOI: 10.1159/000488713
Abstract: b i Background/Aims: /i /b Docetaxel is currently the first-line chemotherapeutic agent available for the treatment of patients with advanced prostate cancer (PCa). While docetaxel has been shown to modestly improve survival times for patients they also experience significant docetaxel-induced toxicities. If treatment failure occurs, there are currently limited alternatives that show survival benefits for patients and therefore there is an urgent need for adjunct therapies. Some quinazoline-based alpha1-adrenoceptor (ADR) antagonists have previously been shown to have cytotoxic actions in PCa cells, but there is no research into their effects on docetaxel-induced toxicity. Therefore, the aim of this study was to determine if the quinazoline ADR, prazosin influenced the sensitivity of PCa cells to docetaxel in vitro. We hypothesised that prazosin, but not tamsulosin, in combination with docetaxel would possess synergistic cytotoxic actions on PC-3 and LNCaP PCa cells. b i Methods: /i /b PC-3 and LNCaP cells were pre-treated (1 h) with prazosin (30 µmol/L) or tamsulosin (30 µmol/L), followed by docetaxel (12.5–100 μmol/L) for 24 h. Docetaxel-induced toxicity was measured in terms of changes in cell proliferation, autophagy, apoptosis and the production of reactive oxygen species (ROS). b i Results: /i /b Prazosin sensitised both cell lines (PC-3 and LNCaP) to docetaxel-induced toxicity. This effect appears to be mediated by autophagy and may also involve apoptosis. These sensitising effects of prazosin appear to be largely independent of ROS production. In contrast, tamsulosin did not affect docetaxel-induced toxicity. b i Conclusion: /i /b We have shown for the first time that prazosin increases docetaxel-induced toxicity in PC-3 and LNCaP cells. Prazosin may therefore offer a viable treatment option in combination with docetaxel in metastatic PCa.
Publisher: Elsevier BV
Date: 08-1991
DOI: 10.1016/0014-2999(91)90329-O
Abstract: Experiments were performed in rats which had been pretreated with amiodarone 50 mg kg-1 day-1 p.o. for 4 weeks. In anaesthetized animals subject to 25 min of coronary artery occlusion, the rats which had received amiodarone had fewer ischaemia-induced ventricular premature beats than the controls (381 +/- 106 compared with 815 +/- 215, P = 0.070). The duration of arrhythmias induced by reperfusion following 5 min of ischaemia was also less in the rats which had received amiodarone than in the controls (43.8 +/- 6.8 and 16.0 +/- 3.1 s respectively). Pretreatment of rats with amiodarone reduced the maximum driving frequency of both isolated left atria and papillary muscles. There were no differences between the responses to alpha- or beta-adrenoceptor agonists or to calcium in papillary muscle preparations from amiodarone-pretreated and control rats. These results suggest that the antiarrhythmic activity of chronic amiodarone seen in the present study does not depend on changes in ventricular adrenoceptor responsiveness.
Publisher: Wiley
Date: 06-2002
DOI: 10.1046/J.1474-8673.2002.00258.X
Abstract: 1. The parasympathetic nervous system is responsible for maintaining normal bladder function, contracting the bladder smooth muscle (detrusor) and relaxing the bladder outlet during micturition. 2. Contraction of the bladder involves direct contraction via M3 receptors and an indirect 're-contraction' via M2-receptors whereby a reduction in adenylate cyclase activity reverses the relaxation induced by beta-adrenoceptor stimulation. 3. Muscarinic receptors are also located on the epithelial lining of the bladder (urothelium) where they induce the release of a diffusible factor responsible for inhibiting contraction of the underlying detrusor smooth muscle. The factor remains unidentified but is not nitric oxide, a cyclooxygenase product or adenosine triphosphate. 4. Finally, muscarinic receptors are also located prejunctionally in the bladder on cholinergic and adrenergic nerve terminals, where M1-receptors facilitate transmitter release and M2 or M4-receptors inhibit transmitter release. 5. In pathological states, changes may occur in these receptor systems resulting in bladder dysfunction. Muscarinic receptor antagonists are the main therapeutic agents available for treatment of the overactive bladder, but whether their therapeutic effect involves actions at all three locations (detrusor, prejunctional, urothelial) has yet to be established.
Publisher: Wiley
Date: 12-09-2006
DOI: 10.1111/J.1474-8673.2006.00374.X
Abstract: Sympathetically mediated urethral tone is essential for the maintenance of continence and involves the activation of postjunctional alpha(1)-adrenoceptors. This study characterizes the alpha(1)-adrenoceptor subtypes responsible for mediating contraction of the urethral circular smooth muscle of the pig. The potency order of a number of agonists and the affinities of several receptor selective antagonists were determined on pig-isolated circular smooth muscle strips in the presence of cocaine (1 microm) and corticosterone (10 microm) to inhibit amine uptake and propranolol (1 microm) to antagonize beta-adrenoceptors. The potency order for agonists was N-[5-(4,5-dihydro-1H-imidazol-2yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulphonamide (A61603) > noradrenaline = phenylephrine = M6434 > methoxamine with pEC(50) values of 7.3, 5.8, 5.7, 5.6 and 5.0 respectively. 4 The alpha(1D)-adrenoceptor-selective antagonist 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4,5]decane-7,9-dione (BMY7378) caused rightward shifts of the concentration-response curves to noradrenaline, yielding a low affinity estimate (6.6) for the urethral receptor. The alpha(1A)-adrenoceptor-selective antagonists, RS100329 and 5-methylurapidil, gave relatively high affinity estimates (9.6 and 8.8 respectively) for this receptor. All three antagonists produced Schild plots with slopes close to unity but did reduce maximum responses at higher concentrations. Prazosin antagonized responses of the urethra to noradrenaline, yielding a mean affinity estimate of 9.0. Although the Schild plot for prazosin again had a slope of unity, this drug also reduced maximum responses to noradrenaline at all concentrations examined (10-100 nm). N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha,alpha-dimethyl-1H-indole-3-ethanamide (RS17053), which discriminates between responses mediated via alpha(1A) (high affinity) and alpha(1L)-adrenoceptors (low affinity) at concentrations up to 3 microm, failed to antagonize responses of the urethra. 5 These results suggest that contraction of urethral circular smooth muscle in the pig is mediated via a single population of adrenoceptors with the pharmacological characteristics of the alpha(1A/L)-adrenoceptor, most probably the alpha(1L)-adrenoceptor.
Publisher: Wiley
Date: 10-2001
DOI: 10.1046/J.1365-2680.2001.00231.X
Abstract: 1 The objective was to determine the role of muscarinic receptor subtypes in mediating contraction of the human detrusor smooth muscle in vitro. 2 Contractile responses of human detrusor muscle strips to carbachol were obtained in the absence and presence of a range of muscarinic antagonists (pirenzepine, methoctramine, 4-diphenylacetoxy-N-methyl piperidine methiodide (4-DAMP), tropicamide, oxybutynin and tolterodine). Affinity estimates (pKB values) were calculated for the antagonists and correlated with values at the cloned muscarinic receptor subtypes quoted in the literature. 3 Pirenzepine, methoctramine and tropicamide drugs that have high affinities at M1, M2 and M4-receptors, respectively, all had low affinities on the human detrusor (pKB values of 6.8, 6.9 and 6.5, respectively), whilst the M3-selective antagonist 4-DAMP had a high affinity (9.5). Schild plots for all four antagonists had slopes of unity indicating an action at a single receptor. Oxybutynin and tolterodine also acted as competitive antagonists with affinity estimates of 7.6 and 8.1, respectively. 4 When the antagonist affinities obtained on the bladder were plotted against the values published for these antagonists at the cloned muscarinic receptor subtypes, the best correlations were obtained for the m3- and m5-muscarinic receptor subtypes. 5 These data suggest that direct contractile responses of the human detrusor muscle to muscarinic receptor stimulation in vitro are mediated solely via the M3-muscarinic receptor subtype with no contribution from the major M2-receptor population.
Publisher: Elsevier BV
Date: 66
DOI: 10.1016/J.EJPHAR.2012.11.053
Abstract: Intravesical treatment with cytotoxic drugs such as doxorubicin is associated with local adverse effects in bladder cancer patients. Here we investigate the effects of doxorubicin on urothelial release of ATP, acetylcholine and prostaglandin E(2), and production of inflammatory cytokines. Urothelial cells were treated with doxorubicin for 1h at 37 °C. Immediately or 24 h following treatment the level of ATP, acetylcholine and prostaglandin E(2) released under basal and stimulated conditions was measured and compared to release from vehicle treated control cultures. The presence of inflammatory cytokines, in culture medium was also assessed 24 h after doxorubicin pre-treatment. Immediately following treatment, stimulated ATP release was inhibited at doxorubicin concentrations ≥1 μg/ml and showed partial recovery at 24 h. Immediately following treatment, basal acetylcholine release was increased by doxorubicin at its clinical concentration (1 mg/ml), while a concentration-dependent decrease in stimulated acetylcholine release was observed. Twenty four hour after treatment, basal acetylcholine release was increased in culture treated with 0.01 mg/ml doxorubicin while stimulated acetylcholine release remained depressed. A significant increase in prostaglandin E(2) release was observed in cells immediately and 24 h after treatment with doxorubicin. A 5.5- and 2-fold increase in interleukin -8 and -1β secretion, respectively was detected 24 h following doxorubicin treatment. These findings indicate that inflammatory cytokines interleukin-8 and -1β are induced and urothelial mediator release is affected by treatment with doxorubicin at clinically relevant concentrations and durations of treatment. These changes may play a role in the adverse effects associated with intravesical doxorubicin treatment.
Publisher: Springer Science and Business Media LLC
Date: 12-1987
DOI: 10.1007/BF00165755
Abstract: Endometrioid carcinoma of the ovary is one of the most types of epithelial ovarian cancer associated to endometrioisis. Endometrioid tumors as well as endometriotic implants are characterized by the presence of epithelial cells, stromal cells, or a combination of booth, that resemble the endometrial cells, suggesting a possible endometrial origin of these tumors. Pro-inflammatory cytokines, including interleukin-1 (IL-1) have been reported to be involved in both endometriosis and ovarian carcinogenesis. The major objective of this study was to determine the level expression of IL-1 ligands system (IL-1alpha, IL-1beta and IL-1RA) in the most common subtypes of ovarian cancer cells compared to endometrial cells. We used primary endometrial cells, endometrial cell line RL-952 and different subtypes of epithelial ovarian cancer cell lines including TOV-112D (endometrioid), TOV-21G (clear cell) and OV-90 (serous). Immunofluorescence and real-time PCR analysis were used respectively for detecting IL-1 ligands at the levels of cell-associated protein and mRNA. Soluble IL-1 ligands were analyzed by ELISA. We demonstrated that IL-1 ligands were expressed by all endometriosis-associated ovarian cancer subtypes and endometrial cells. In contrast to other cancer ovarian cells, endometrioid cells exhibit a specific decrease of cell-associated IL-1RA expression and its soluble secretion. Endometrioid ovarian cancer exhibits an alteration in the expression of IL-1RA, a key protector against tumorogenic effects of IL-1. This alteration evokes the same alteration observed in endometriotic cells in previous studies. This suggests a possible link between the endometrium, the tissue ectopic endometriosis and endometrioid ovarian cancer.
Publisher: Oxford University Press (OUP)
Date: 12-1986
DOI: 10.1111/J.2042-7158.1986.TB03380.X
Abstract: Chronic catecholamine depletion induced by reserpine pretreatment of rats, or 6-hydroxydopamine pretreatment of guinea-pigs, resulted in an enhanced sensitivity of isolated papillary muscles to isoprenaline. This hypersensitivity was accompanied by l.41-(rats) and 1.52-fold (guinea-pigs) increases in the number of [3H]dihydroalprenolol binding sites, without changes in binding affinity. An equation was derived for calculation of increases in receptor number. Application of this showed that substantially greater increases in receptor number were required (2.32- to 4.04-fold) to account for the degree of supersensitivity observed.
Publisher: Elsevier BV
Date: 03-2006
DOI: 10.1016/J.EURURO.2005.11.028
Abstract: The role of tachykinins such as neurokinin A in regulating bladder function is unclear, but NK2 receptors seem to mediate contraction in the human bladder and it has been suggested that these peptides may have a role in the pathophysiology of bladder dysfunction. The present study investigates neurokinin receptor-mediated contractility of detrusor muscle in the idiopathic overactive and neurogenic overactive bladder and investigates the neurokinin receptor subtypes involved. Human bladder was obtained from patients undergoing cystectomy (normal) or clam cystoplasty (idiopathic overactive) and from patients with spinal injuries (neurogenic overactive). Strips of isolated detrusor muscle were mounted in physiological Krebs-bicarbonate solution and cumulative concentration-response curves to 1 nM to 300 microM neurokinin A (NKA) were obtained in the absence and presence of neurokinin receptor antagonists, either the NK2 receptor-selective antagonist SR 48968 or the NK3 receptor-selective antagonist SB 223412. NKA evoked concentration-dependent contraction of normal, idiopathic, and neurogenic overactive detrusor strips. In idiopathic overactive detrusor muscle, NKA-induced contraction was significantly reduced relative to normal detrusor (0.031 +/- 0.005 mg/g, n = 11 versus 0.193 +/- 0.039 mg/g, n = 7). Sensitivity to the peptide was also significantly (p < 0.01) reduced in idiopathic overactive detrusor, with mean pEC50 values (concentration producing 50% maximal response) of 6.62+/-0.16 (n = 11) compared to 7.47+/-0.19 (n = 7) in normal detrusor. In contrast, NKA-induced responses of neurogenic overactive detrusor were similar to those in normal detrusor, with a mean maximum contraction of 0.199 +/- 0.036 mg/g (n = 10) and mean pEC50 value of 7.85+/-0.16 (n = 10). NKA curves in all groups were shifted to the right by the NK2 receptor-selective antagonist SR 48968 with high affinity, pK(B) values being similar in normal, idiopathic, and neurogenic overactive detrusor (8.85 + 0.08, n = 14 8.97 +/- 0.13, n = 12 8.73 +/- 0.12, n = 8, respectively). In contrast the NK3 receptor-selective antagonist SB 223412 had a minimal effect on NKA responses and affinity values were low (pK(B) 5.81 +/- 0.11, n = 12 in normal 5.75 +/- 0.08, n = 12 in idiopathic overactive, and 5.77 +/- 0.13, n = 11 in neurogenic overactive). These data indicate that NKA-induced responses are impaired in detrusor muscle from idiopathic overactive human bladder, but not in detrusor muscle from neurogenic overactive bladder. The NK2 receptor subtype appears to mediate NKA responses in the normal, idiopathic overactive, and neurogenic overactive detrusor. This is important evidence suggesting a difference between the bladder pathophysiology observed in idiopathic versus neurogenic overactive detrusor.
Publisher: Elsevier BV
Date: 05-1990
DOI: 10.1016/0022-2828(90)90961-Z
Abstract: Guinea-pig isolated hearts were perfused by the Langendorff method. Low flow (10%) global ischaemia for 30 min induced ventricular tachycardia (VT) and fibrillation (VF) in 87.5 and 37.5% respectively of the hearts. The onset times for VT and VF were 15.7 +/- 1.0 and 23.5 +/- 1.6 min respectively. On reperfusion the incidences of VT and VF were 81.3 and 75.0% and occurred after 16.0 +/- 1.5 and 35.0 +/- 4.9 s of reperfusion. In those hearts exhibiting arrhythmias, [3H]-prazosin binding to alpha 1-adrenoceptors of ventricular membrane fractions was measured and compared with normally perfused time-matched controls. There was no significant change in dissociation constant (KD) or density Bmax, of binding throughout the control perfusion period. Similarly, the KD (0.38 +/- 0.06 nM) and Bmax (15.5 +/- 1.4 fmol/mg protein) values obtained during ischaemia did not differ significantly from the corresponding control values (0.48 +/- 0.05 nM and 15.8 +/- 1.5 fmol/mg protein). Also, at 1 min of reperfusion the KD (0.42 +/- 0.04 nM) and Bmax (19.3 +/- 2.0 fmol/mg protein) values were not significantly different from the time-matched controls (0.38 +/- 0.09 nM and 20.1 +/- 2.6 fmol/mg protein). The same result was obtained if the crude membrane fraction pelleted by the initial slow spin was used. Thus, although cardiac arrhythmias are induced by ischaemia and reperfusion of the guinea-pig isolated perfused heart and previous studies have shown these to be susceptible to alpha-adrenoceptor blockade, they are not accompanied by an increase in alpha 1-adrenoceptor affinity or density.
Publisher: Wiley
Date: 17-07-2018
Abstract: Up to 80% of patients with diabetes mellitus develop lower urinary tract complications, most commonly diabetic bladder dysfunction (DBD). The aim of this study was to investigate the impact of diabetes on the function of the inner bladder lining (urothelium). Bladder compliance and intraluminal release of urothelial mediators, adenosine triphosphate (ATP) and acetylcholine (ACh) in response to distension were investigated in whole bladders isolated from 2- and 12-week streptozotocin (STZ)-diabetic rats. Intact and urothelium-denuded bladder strips were used to assess the influence of the urothelium on bladder contractility. Intraluminal ATP release was significantly enhanced at 2 weeks of diabetes, although not at 12 weeks. In contrast, intraluminal ACh release was unaltered by diabetes. Bladder compliance was also significantly enhanced at both 2 and 12 weeks of diabetes, with greatly reduced intravesical pressures in response to distension. Nerve-evoked contractions of bladder strips were significantly greater at 2 weeks of diabetes. When the urothelium was absent, nerve-evoked contractions were reduced, but contractions remained significantly elevated at lower frequencies of stimulation (<5 Hz) in diabetics. Interestingly, although relaxations of bladder strips to isoprenaline were unaltered by diabetes, removal of the urothelium unmasked significantly enhanced relaxations in strips from 2- and 12-week diabetic animals. In conclusion, diabetes alters urothelial function. Enhanced urothelial ATP release may be involved in the hypercontractility observed at early time points of diabetes. These alterations are time-dependent and may contribute to the mechanisms at play during the development of diabetic bladder dysfunction.
Publisher: Wiley
Date: 03-1993
DOI: 10.1111/J.1476-5381.1993.TB12857.X
Abstract: 1. Noradrenaline and isoprenaline were infused subcutaneously in rats by use of Alzet osmotic minipumps. The effects of catecholamine infusion on ventricular alpha- and beta-adrenoceptor density and also the responses of isolated cardiac tissues were compared with saline infusion. 2. Noradrenaline (1 mg kg-1) or isoprenaline (40 micrograms kg-1) infused for 3 days resulted in a desensitization of beta-adrenoceptor-mediated responses of isolated left atria and papillary muscles. Concentration-response curves to isoprenaline were shifted to the right in left atria whilst maximum responses were reduced in papillary muscles. Right atrial rate responses were not affected by infusions of catecholamines. 3. Infusions of either noradrenaline or isoprenaline resulted in a supersensitivity of alpha-adrenoceptor-mediated responses in isolated papillary muscles with leftward displacements of concentration-response curves to phenylephrine. 4. The density of both ventricular [3H]-dihydroalprenolol and [3H]-prazosin binding sites was reduced following noradrenaline infusion. Isoprenaline infusion reduced only the density of [3H]-dihydroalprenolol binding sites. 5. Noradrenaline infusion therefore 'down-regulates' both alpha- and beta-adrenoceptors in the rat heart but at the same time ventricular alpha-adrenoceptor-mediated responses are enhanced. Isoprenaline similarly enhances responses to phenylephrine and possible mechanisms for this phenomenon are discussed.
Publisher: Wiley
Date: 05-1999
Publisher: Wiley
Date: 27-10-2003
DOI: 10.1046/J.1464-410X.2003.04458.X
Abstract: To investigate the role of neurokinin (NK)-2 and -3 receptors in mediating the contraction of detrusor muscle strips from human and pig, to determine whether the pig is a good model for the study of tachykinin receptors in the human bladder, as the biological actions of tachykinins, e.g. substance P and NKA are mediated via three distinct receptor subtypes, NK-1, -2 and -3. Strips of detrusor muscle were obtained from the bladder dome and neck of female pigs and from patients undergoing cystectomy. Cumulative concentration-response curves to NKA were obtained in the absence and presence of either the NK-2 receptor-selective antagonist SR48968 or the NK-3 receptor-selective antagonist SB223412. NKA produced concentration-dependent contractions in the human and pig detrusor muscle the curves were shifted to the right by SR48968, with high affinity (pKB 8.9, 8.3 and 8.0 in the human, pig dome and pig neck, respectively), whereas SB223412 had a minimal effect (pKB 5.8, 5.8 and 6.3, respectively). These data confirm that the NK-2 receptor subtype mediates NKA-induced contraction of the human and pig detrusor muscle. The NK-3 receptor appears to have no role in detrusor contraction of either species. The results also provide evidence that the NK-2 receptor in human and pig are the same, and the latter may be an appropriate species to study tachykinin-induced contractions in human bladder.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2012
DOI: 10.1016/J.JURO.2011.10.129
Abstract: We determined the effects of Pseudomonas aeruginosa virulence factor pyocyanin on human urothelial cell viability and function in vitro. RT4 urothelial cells were treated with pyocyanin (1 to 100 μM) for 24 hours. After exposure the treatment effects were measured according to certain end points, including changes in urothelial cell viability, reactive oxygen species formation, caspase-3 activity, basal and stimulated adenosine triphosphate release, SA-β-gal activity and detection of acidic vesicular organelles. The 24-hour pyocyanin treatment resulted in a concentration dependent decrease in cell viability at concentrations of 25 μM or greater, and increases in reactive oxygen species formation and caspase-3 activity at 25 μM or greater. Basal adenosine triphosphate release was significantly decreased at all tested pyocyanin concentrations while stimulated adenosine triphosphate release was significantly inhibited at pyocyanin concentrations of 12.5 μM or greater with no significant stimulated release at 100 μM. Pyocyanin treated RT4 cells showed morphological characteristics associated with cellular senescence, including SA-β-gal expression. This effect was not evident at 100 μM pyocyanin and may have been due to apoptotic cell death, as indicated by increased caspase-3 activity. An increase in acridine orange stained vesicular-like organelles was observed in RT4 urothelial cells after pyocyanin treatment. Exposure to pyocyanin alters urothelial cell viability, reactive oxygen species production and caspase-3 activity. Treatment also results in cellular senescence, which may affect the ability of urothelium to repair during infection. The virulence factor depressed stimulated adenosine triphosphate release, which to our knowledge is a novel finding with implications for awareness of bladder filling in patients with P. aeruginosa urinary tract infection.
Publisher: Springer Science and Business Media LLC
Date: 24-02-2015
DOI: 10.1007/S00210-015-1104-7
Abstract: Docetaxel was the first chemotherapeutic agent to increase survival time in patients with androgen-resistant prostate cancer. However, it provides only a modest increase in survival and is associated with significant toxicity. Therefore, there is an urgent need to identify potential adjunct therapies. Given the key role of autophagy in both tumour survival and chemoresistance, the impact of autophagy modulation on docetaxel toxicity was tested in vitro. PC-3 and LNCaP cells were pre-treated with the autophagy inhibitor 3-methyladenine (5 mM) and then exposed to various concentrations (0-100 μM) of docetaxel. Cytoxic effects of docetaxel were measured using resazurin reduction to resorufin, whilst autophagy and apoptosis was measured using monodansylcadaverine, annexin V and caspase-3, respectively. Docetaxel produced significant toxicity in PC-3 cells but was not toxic to LNCaP cells. Pre-treatment with the autophagy inhibitor, 3-methyladenine (5 mM) significantly protected PC-3 cells against docetaxel-induced cytotoxicity, increased autophagosome formation and apoptosis measured using monodansylcadaverine, annexin V and caspase-3 fluorescence, respectively. In contrast, 3-methyladenine was toxic by itself in LNCaP cells and also increased autophagic vesicle formation and apoptosis but did not influence docetaxel toxicity in these cells. These paradoxical effects of 3-methyladenine were largely independent of reactive oxygen species production. We show here that modulation of autophagy may influence docetaxel-induced toxicity in prostate cancer cells and these effects may differ between cell lines.
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.JPHS.2018.08.003
Abstract: α
Publisher: Wiley
Date: 02-1991
DOI: 10.1111/J.1474-8673.1991.TB00241.X
Abstract: 1. The chronotropic and inotropic responses of the young chick heart to noradrenaline have been investigated in isolated right atria, left atria and ventricular strips from 14-day-old chicks. 2. In the presence of desipramine and metanephrine to inhibit amine uptake, concentration-response curves to noradrenaline in all three tissues were shifted to the right by propranolol (1 microM) but were not altered by the presence of either phentolamine (5 microM) or prazosin (10 microM). 3. Similar results were obtained in the presence of cocaine (10 microM) and corticosterone (10 microM) to inhibit amine uptake. Propranolol (0.3-3.0 microM) produced rightward shifts of noradrenaline concentration-response curves which gave pA2 values of 8.1-8.4. Phentolamine (5 microM), in contrast, did not affect responses to noradrenaline in any tissue, either in the absence or presence of propranolol (1 microM). 4. Isoprenaline produced positive chronotropic responses in right atria and positive inotropic responses in left atria and ventricular strips. Methoxamine elicited positive inotropic responses in left atria but only negative chronotropic responses in right atria and negative inotropic responses in ventricular strips. 5. These results demonstrate that cardiac responses to noradrenaline in the chick heart are mediated via beta-adrenoceptors only, and that cardiac alpha-adrenoceptors are not involved in these responses.
Publisher: Wiley
Date: 11-1996
DOI: 10.1111/J.1476-5381.1996.TB16009.X
Abstract: 1. The affinity of the alpha 1-adrenoceptor antagonist SB 216469 (also known as REC 15/2739) has been determined at native and cloned alpha 1-adrenoceptor subtypes by radioligand binding and at functional alpha 1-adrenoceptor subtypes in isolated tissues. 2. In radioligand binding studies with [3H]-prazosin, SB 216469 had a high affinity at the alpha 1A-adrenoceptors of the rat cerebral cortex and kidney (9.5-9.8) but a lower affinity at the alpha 1B-adrenoceptors of the rat spleen and liver (7.7-8.2). 3. At cloned rat alpha 1-adrenoceptor subtypes transiently expressed in COS-1 cells and also at cloned human alpha 1-adrenoceptor subtypes stably transfected in Rat-1 cells, SB 216469 exhibited a high affinity at the alpha 1a-adrenoceptors (9.6-10.4) with a significantly lower affinity at the alpha 1b-adrenoceptor (8.0-8.4) and an intermediate affinity at the alpha 1d-adrenoceptor (8.7-9.2). 4. At functional alpha 1-adrenoceptors, SB 216469 had a similar pharmacological profile, with a high affinity at the alpha 1A-adrenoceptors of the rat vas deferens and anococcygeus muscle (pA2 = 9.5-10.0), a low affinity at the alpha 1B-adrenoceptors of the rat spleen (6.7) and guinea-pig aorta (8.0), and an intermediate affinity at the alpha 1D-adrenoceptors of the rat aorta (8.8). 5. Several recent studies have concluded that the alpha 1-adrenoceptor present in the human prostate has the pharmacological characteristics of the alpha 1A-adrenoceptor subtype. However, the affinity of SB 216469 at human prostatic alpha 1-adrenoceptors (pA2 = 8.1) determined in isolated tissue strips, was significantly lower than the values obtained at either the cloned alpha 1a-adrenoceptors (human, rat, bovine) or the native alpha 1A-adrenoceptors in radioligand binding and functional studies in the rat. 6. Our results with SB 216469, therefore, suggest that the alpha 1-adrenoceptor mediating contractile responses of the human prostate has properties which distinguish it from the cloned alpha 1a-adrenoceptor or native alpha 1A-adrenoceptor. Since it has previously been shown that the receptor is not the alpha 1B- or alpha 1D-adrenoceptor, the functional alpha 1-adrenoceptor of the human prostate may represent a novel receptor with properties which differ from any of the alpha 1-adrenoceptors currently defined by pharmacological means.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2003
DOI: 10.1097/00042307-200307000-00004
Abstract: Detrusor overactivity is a relatively common yet embarrassing symptom complex with significant impact on quality of life. The mainstay of current pharmacological treatment involves use of muscarinic receptor antagonists, but their therapeutic efficacy is limited by their troublesome side effects resulting in the non-continuance of treatment in a significant number of patients. Therefore, the development of new drugs can proceed by targeting alternative pathways affecting detrusor overactivity. In this article, the pharmacological basis for the current therapeutic alternatives for managing detrusor overactivity and possible future developments are discussed. It is clear that far from being a passive container for urine, the urothelium is a crucial part of the bladder. Its functions are complex, dynamic and important, and only now becoming understood. The release of ATP from urothelium in response to distension and its action on P2X receptors resulting in activating both motor and sensory neurons is being increasingly recognised. In the normal bladder, muscarinic receptor stimulation produces the main part of detrusor contraction. However, in functionally abnormal bladders, a non-cholinergic activation via the purinergic receptors may occur. The central nervous mechanisms controlling the micturition reflex have also recently attracted attention. Recent research has suggested that several transmitters may modulate voiding. However, few drugs with clinical benefits have been developed so far. Present treatments for overactive bladders have significant non-compliance rates. Hopefully, future research will lead to drugs with greater therapeutic benefits and better tolerance.
Publisher: Elsevier BV
Date: 07-2020
Publisher: Wiley
Date: 07-02-2219
Publisher: Springer Science and Business Media LLC
Date: 09-01-2018
DOI: 10.1038/S41598-017-18136-W
Abstract: Both TRPV1 and P2X receptors present on bladder sensory nerve fibres have been implicated in mechanosensation during bladder filling. The aim of this study was to determine possible interactions between these receptors in modulating afferent nerve activity. In wildtype (TRPV1 +/+ ) and TRPV1 knockout (TRPV1 −/− ) mice, bladder afferent nerve activity, intravesical pressure, and luminal ATP and acetylcholine levels were determined and also intracellular calcium responses of dissociated pelvic DRG neurones and primary mouse urothelial cells (PMUCs). Bladder afferent nerve responses to the purinergic agonist αβMethylene-ATP were depressed in TRPV1 −/− mice (p ≤ 0.001) and also in TRPV1 +/+ mice treated with the TRPV1-antagonist capsazepine (10 µM p ≤ 0.001). These effects were independent of changes in bladder compliance or contractility. Responses of DRG neuron to αβMethylene-ATP (30 µM) were unchanged in the TRPV1 −/− mice, but the proportion of responsive neurones was reduced (p ≤ 0.01). Although the TRPV1 agonist capsaicin (1 µM) did not evoke intracellular responses in PMUCs from TRPV1 +/+ mice, luminal ATP levels were reduced in the TRPV1 −/− mice (p ≤ 0.001) compared to wildtype. TRPV1 modulates P2X mediated afferent responses and provides a mechanistic basis for the decrease in sensory symptoms observed following resiniferatoxin and capsaicin treatment for lower urinary tract symptoms.
Publisher: Wiley
Date: 10-2000
DOI: 10.1046/J.1464-410X.2000.00868.X
Abstract: To determine whether detrusor muscle from the pig can be used as a model to study presynaptic 5-hydroxytryptamine (HT)4-receptor-mediated effects on the electrical field stimulated (EFS) cholinergic responses previously identified in the human bladder. Materials and methods Strips of detrusor muscle were mounted in physiological Krebs' solution under 1 g tension and field stimulated (25 Hz, 0.01 ms duration, 60 V for 5 s) at 100-s intervals and allowed to equilibrate. Concentration-response curves to 5-HT (1 nmol/L to 300 micromol/L) were constructed in the presence and absence of the 5-HT4-selective antagonists RS-100235 and GR-113808 (both at 0.3, 1 and 3 nmol/L). All experiments were conducted in the presence of methiothepin and ondansetron (both 1 micromol/L) to block 5-HT1, -HT2 and -HT3 receptors. 5-HT potentiated the cholinergic responses to EFS in pig bladder strips in a concentration-dependent manner, with a maximum mean (SEM) potentiation of 48.3 (7.7)% of the resting tension (n = 25). Both RS-100235 and GR-113808 antagonized the effect of 5-HT with high affinity, yielding apparent pKB values which were consistent with the responses being mediated via the 5-HT4 receptor subtype. These data indicate that 5-HT can potentiate EFS responses in isolated pig bladder strips and that the 5-HT4 receptor subtype mediates this response. Therefore, the pig may be used as an effective model to study presynaptic 5-HT4 receptors previously reported in the human bladder.
Publisher: Springer Science and Business Media LLC
Date: 22-05-2020
Publisher: Springer Science and Business Media LLC
Date: 11-2001
DOI: 10.1007/PL00007102
Abstract: Muscarinic receptor antagonists remain the main therapy for the treatment of the overactive bladder yet severe adverse effects make them unsuitable for a large number of patients. The development of new drugs with novel mechanisms of action for the treatment of this condition is therefore essential. This article considers some of the targets currently under investigation for the development of such compounds. Beta-adrenoceptor agonists and KATP channel openers inhibit detrusor muscle activity and remain targets for drug development. There is also evidence that alpha-adrenoceptor antagonists may be effective in the overactive bladder, but the mechanism involved in this action is unclear. Finally the role of tachykinins in regulating bladder function through both the sensory and the motor innervation make them a potential target for drug development, but as with the the others, a selective action on the bladder must remain the goal of drug development.
Publisher: Wiley
Date: 09-2004
Publisher: Wiley
Date: 12-1993
Publisher: JMIR Publications Inc.
Date: 09-08-2018
DOI: 10.2196/10012
Publisher: Informa UK Limited
Date: 1987
DOI: 10.3109/10799898709056781
Abstract: Alpha 1- and beta-adrenoceptor responsiveness and binding have been examined in cardiac tissues removed from guinea-pigs pretreated with 6-hydroxydopamine (6-OHDA) for 3 weeks. Results were compared with control tissues from sham-injected animals. Chemical sympathectomy with 6-OHDA resulted in an increase in the sensitivity of postjunctional beta-adrenoceptor-mediated responses to isoprenaline. No such increase was observed for the alpha 1-adrenoceptor-mediated responses to methoxamine. The increase in beta-adrenergic responsiveness was accompanied by a significant (P less than 0.05) 52% increase in the number of [3H]-dihydroalprenolol binding sites with no change in binding affinity. [3H]-Prazosin binding was not affected by pretreatment with 6-OHDA. The results suggest that cardiac beta- but not alpha 1-adrenergic responsiveness is regulated by the sympathetic innervation.
Publisher: Wiley
Date: 10-2002
DOI: 10.1046/J.1474-8673.2002.00272.X
Abstract: 1 The aim of the study was to investigate the role of the α 1D ‐adrenoceptor in α 1 ‐adrenoceptor‐induced contraction of human prostate by means of protection experiments. 2 Responses of human prostate strips to noradrenaline were recorded, along with responses of rat aorta and vas deferens, tissues possessing predominantly α 1D ‐ and α 1A ‐adrenoceptors respectively, for comparison. α 1 ‐adrenoceptors were then inactivated by incubation with the irreversible antagonist phenoxybenzamine. In some tissues α 1A ‐ or α 1D ‐adrenoceptors were ‘protected’ from inactivation by incubation in the presence of the selective α 1A ‐ or 1D ‐adrenoceptor antagonists 5‐methylurapidil and BMY 7378 before recording further responses to noradrenaline. 3 Phenoxybenzamine reduced the maximum noradrenaline‐induced response and the potency of noradrenaline in all tissues. In rat vas deferens and human prostate, 5‐methylurapidil protected α 1A ‐adrenoceptors in a concentration–dependent manner. In rat aorta, 10 n m BMY 7378 almost fully protected α 1D ‐adrenoceptors. However, concentrations of BMY 7378 up to 30‐fold higher failed to protect receptors in the human prostate. 4 These results suggest that in human prostate functional α 1D ‐adrenoceptors do not contribute to noradrenaline‐induced contractile responses.
Publisher: MDPI AG
Date: 24-09-2022
DOI: 10.3390/JCM11195637
Abstract: Prostate cancer (PCa) is the second most commonly diagnosed cancer worldwide. Radiotherapy remains one of the first-line treatments in localised disease and may be used as monotherapy or in combination with other treatments such as androgen deprivation therapy or radical prostatectomy. Despite advancements in delivery methods and techniques, radiotherapy has been unable to totally overcome radioresistance resulting in treatment failure or recurrence of previously treated PCa. Various factors have been linked to the development of tumour radioresistance including abnormal tumour vasculature, oxygen depletion, glucose and energy deprivation, changes in gene expression and proteome alterations. Understanding the biological mechanisms behind radioresistance is essential in the development of therapies that are able to produce both initial and sustained response to radiotherapy. This review will investigate the different biological mechanisms utilised by PCa tumours to drive radioresistance.
Publisher: Cold Spring Harbor Laboratory
Date: 27-12-2219
DOI: 10.1101/2019.12.27.889329
Abstract: The role of the small GTPase RAB27A as an essential melanosome trafficking regulator in melanocytes is well-accepted. A decade ago, RAB27A was identified as a tumor dependency gene that promotes melanoma cell proliferation. RAB27A has since been linked to another propeller of cancer progression: exosome secretion. We have recently demonstrated that RAB27A is overexpressed in a subset of melanomas. High RAB27A gene and protein expression correlates with poor prognosis in melanoma patients. Mechanistic investigations revealed that the generation of pro-invasive exosomes was RAB27A-dependent and, therefore, silencing RAB27A reduced melanoma cell invasion in vitro and in vivo . However, previous studies have implicated RAB27A to be involved in both proliferation and invasion of melanoma cells. In this study, we demonstrate that the effects of abrogating RAB27A expression on proliferation are temporary, in contrast to the previously reported persistent effects on tumor invasion and metastasis. Therefore, we assist in the dissection of the short-term versus long-term effects of RAB27A knockdown on melanoma cell proliferation, invasion, and metastasis. We believe that our findings provide novel insights into the effects of RAB27A blockade. RAB27A is known to serve as an essential regulator for melanosome trafficking. However, to date its role in melanoma biology has not been completely deciphered. While there are consistent independent reports on the pro-invasive effects of RAB27A, there are conflicting data on its impact on cell proliferation. Here we show that indeed abrogation of RAB27A does reduce cellular proliferation however, this effect is only transient, while the impact on invasion as reported previously is persistent. This finding offers an explanation for the apparent contradiction in the literature and provides a deeper understanding of RAB27A function in melanoma cell biology.
Publisher: Elsevier BV
Date: 02-2002
DOI: 10.1016/S0014-2999(02)01263-3
Abstract: The nonselective beta-adrenoceptor agonist, isoprenaline (pD2 8.8 +/- 0.2), and selective beta2-adrenoceptor agonists, clenbuterol (9.2 +/- 0.4) and salbutamol (7.1 +/- 0.1), inhibited the immunoglobulin E-mediated release of histamine from human lung mast cells in a concentration-dependent manner. The beta2-adrenoceptor-selective antagonist, ICI118551 (erythro-(+/- )-1-(7-methylindan-4-yloyl)-3-isopropylaminobutan-2-ol HCl), antagonised the isoprenaline inhibition of histamine release from human lung mast cells with high affinity (apparent pK(B) 9.5 +/- 0.2), whereas high concentrations of the beta1-adrenoceptor-selective antagonist, CGP20712A (2-hydroxy-5-(2-(hydroxy-3-(4((1-methyl-4-trifluoromethyl)-1-H-imidazol-2-yl)-phenoxy)-propyl)-aminoethoxyl)-benzamide), were required to reverse the isoprenaline inhibition (apparent pK(B) 6.5 +/- 0.3). Radioligand binding studies using [125I]-iodocyanopindolol ([125I]CYP) were performed on membranes derived from purified mast cells (>90% purity). Binding of [125I]CYP to mast cell membranes was displaced from a single binding site with a high affinity for ICI118551 (pK(i) 8.9 +/- 0.1) and low affinity for CGP20712A (pK(i) 6.0 +/- 0.03), indicative of a homogeneous population of beta2-adrenoceptors. In contrast, in human lung membranes, these antagonists displaced [125I]CYP from two sites indicative of a heterogeneous population of beta1-adrenoceptors (20%) and beta2-adrenoceptors (80%). These data indicate that the beta-adrenoceptor expressed by human lung mast cells and mediating inhibition of mediator release from these cells is the beta2-adrenoceptor.
Publisher: Oxford University Press (OUP)
Date: 10-1993
DOI: 10.1111/J.2042-7158.1993.TB05623.X
Abstract: The α1-adrenoceptor-mediated responses of the rat prostate to phenylephrine have been examined in-vitro. Phenylephrine induced concentration-dependent contractions of the isolated prostate gland which were antagonized by WB4101 (1–30 nm). Schild plot analysis of the antagonism yielded a straight line with a slope not significantly different from unity. The pKB value of 9·2 was similar to that obtained for WB4101 on the rat vas deferens (9·4) but was greater than that obtained on the rat spleen (8·4). Chloroethyl-clonidine depressed responses to phenylephrine of the rat spleen but not the prostate or the vas deferens. These results indicate that the rat prostate gland possesses a typical α1A-adrenoceptor similar to that found in the vas deferens.
Publisher: Wiley
Date: 19-06-2006
DOI: 10.1111/J.1474-8673.2006.00371.X
Abstract: 1 Bladder smooth muscle sensitivity to muscarinic agonists is increased in the overactive bladder. Treatment of rats with streptozotocin induces a diabetic state in which the bladder muscle is overactive and also supersensitive to muscarinic agonists. This study has examined bladder contraction, muscarinic receptor density and receptor/G-protein coupling in the streptozotocin-induced overactive bladder of the rat. 2 Diabetes was induced by a single intraperitoneal dose of streptozotocin. Seven days later contraction of isolated detrusor muscle strips was assessed in tissue bath experiments, while receptor density was assayed in saturation experiments with [3H]-QNB (quinuclidinyl benzilate, L-[benzilic-4,4'-3H]) and receptor/G-protein coupling was determined in agonist displacement experiments with this radioligand. 3 Isolated detrusor strips from diabetic animals displayed an enhanced degree of spontaneous activity (0.060 +/- 0.016 g mg(-1), compared with 0.015 +/- 0.004 g mg(-1), P < 0.05). Carbachol produced contractile responses in tissues from both control and diabetic rats, but the diabetic tissues were more sensitive to this agonist, the pEC50 being 6.52 +/- 0.17 compared with 5.93 +/- 0.06 in controls (P < 0.001). Maximum responses to carbachol were similar in both groups of animals. The increase in carbachol potency was accompanied by a 40% increase in receptor density from 158 +/- 5 to 221 +/- 22 fmol mg(-1) protein (P < 0.05), but this was not enough to fully account for the change in tissue sensitivity. 4 In the absence of GTP-gamma-S, carbachol displaced [3H]-QNB from two binding sites, the high-affinity site (pKi = 7.06 +/- 0.26) which represents the receptors coupled to G-proteins made up 43.1 +/- 5.9% of the total binding sites in control tissues and this value was similar (41.0 +/- 4.0%) in the diabetic tissues (pKi = 6.64 +/- 0.31). In the presence of GTP-gamma-S, carbachol displaced [3H]-QNB from a single binding site which had a low-affinity, similar to the low-affinity site observed in the absence of GTP-gamma-S. 5 These data demonstrate that detrusor supersensitivity is observed after only 1 week of untreated diabetes in the rat. The overactivity is associated with an enhanced sensitivity to carbachol, which is partly explained by an increase in receptor density, but there appears to be no change in receptor/G-protein coupling.
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.EJPHAR.2017.11.001
Abstract: Isolated ureteral strips develop spontaneous phasic contractile activity which is enhanced by 5-hydroytryptamine (5-HT). The aim of this study was to identify the receptor subtype mediating these responses and to determine whether responses to 5-HT change with age. The frequency of contractions and the overall contractile activity (measured as the area under the curve, AUC) were recorded in strips of porcine distal ureter isolated from young (3 months) and old (2 years) pigs. Responses to 5-HT were examined in the absence and presence of selective 5-HT receptor subtype antagonists. Tissues from the younger animals elicited larger contractile responses to 5-HT (5885 ± 335g
Publisher: Informa Healthcare
Date: 02-2002
Abstract: alpha-adrenoceptor antagonists have traditionally been used in the treatment of hypertension but in recent years they have become increasingly common in the treatment of benign prostatic enlargement (BPE), where they reduce the 'dynamic' component of bladder outlet obstruction and appear to have additional actions to reduce irritative symptoms of the disease. Prazosin (Hypovase), Alza), doxazosin (Cardura), Pfizer), indoramin (Doralese), Wyeth-Ayerst Pharmaceuticals Inc.) and terazosin (Hytrin), Abbott Laboratories) are currently available in the UK for BPE but these agents have cardiovascular actions in a significant number of patients, inducing effects which must be considered adverse unless the patient also requires treatment for mild-to-moderate hypertension. The uroselective alpha-adrenoceptor antagonists tamsulosin (Flomax), Yamanouchi Pharmaceutical Co. Ltd.) and alfuzosin (Xatral), Sanofi-Synthelabo) have recently been introduced. These agents exert their selectivity via different mechanisms selective tissue distribution for alfuzosin and alpha-adrenoceptor subtype selectivity for tamsulosin. The incidence of cardiovascular side effects for both drugs is similar to placebo. Several lines of evidence suggest that the alpha-adrenoceptor antagonists may relieve lower urinary tract (LUT) symptoms by other mechanisms additional to those which account for the reduction in bladder outlet obstruction. If correct, these agents may be of use in the treatment of other bladder conditions.
Publisher: Springer Science and Business Media LLC
Date: 28-05-2018
DOI: 10.1007/S00210-018-1510-8
Abstract: The epithelial inner layer of the lower urinary tract, i.e., the urothelium, and other parts of the mucosa are not just a passive barrier but play an active role in the sensing of stretching, neurotransmitters, paracrine mediators, hormones, and growth factors and of changes in the extracellular environment. We review the molecular and cellular mechanisms enabling the urothelium to sense such inputs and how this leads to modulation of smooth muscle contraction and relaxation. The urothelium releases various mediators including ATP, acetylcholine, prostaglandins, nitric oxide, and nerve growth factor. These may affect function and growth of smooth muscle cells and afferent nerves. However, the molecular identity of the urothelium-derived mediator directly modulating contractile and relaxant responses of isolated bladder strips has remained elusive. The morphology and function of the urothelium undergo changes with aging and in many pathophysiological conditions. Therefore, the urothelium may contribute to the therapeutic effects of established drugs to treat lower urinary tract dysfunction and may also serve as a target for novel therapeutics. However, therapeutics may also change urothelial function, and it is not always easy to determine whether such changes are part of the therapeutic response or reflect secondary alterations.
Publisher: Wiley
Date: 16-06-2021
DOI: 10.1111/LUTS.12395
Abstract: It is well established that lower urinary tract symptoms (LUTS), particularly urinary urgency and incontinence, cause stress and anxiety for patients. However, there is mounting evidence that the relationship between these two factors is bidirectional and that chronic psychological stress itself can result in the development of symptoms such as urinary frequency, urgency, incontinence, and pelvic pain. This review considers the evidence that such a relationship exists and reviews the literature from clinical and animal studies to identify some of the mechanisms that might be involved. Inflammatory responses induced by chronic stress appear to offer the strongest link to bladder dysfunction. There is overwhelming evidence, both in patients and animal models, for a release of pro‐inflammatory cytokines and chemokines during periods of chronic stress. Furthermore, cytokines have been shown to cause bladder dysfunction and pain via actions in the central nervous system and locally in the bladder. In the brain and spinal cord, pro‐inflammatory cytokines influence the regulation of micturition pathways by corticotropin‐releasing factor (CRF) and its receptors, while peripherally cytokines affect bladder function, directly causing detrusor hypertrophy and afferent nerve hypersensitivity. There is little information on which treatments may have most benefit for stressed/anxious patients with LUTS, but animal studies suggest traditional drugs for overactive bladder (solifenacin, mirabegron) are more effective on LUTS than anxiolytic drugs (fluoxetine, imipramine). The preliminary preclinical data for CRF receptor antagonists is not consistent. A clearer understanding of the mechanisms involved in stress‐induced LUTS should provide a basis for improved treatment of this condition.
Publisher: Wiley
Date: 1997
Publisher: Japan Society of Smooth Muscle Research
Date: 2004
DOI: 10.1540/JSMR.40.237
Abstract: The parasympathetic nervous system is responsible for maintaining normal intestinal and bladder function, contracting the smooth muscle by releasing the neurotransmitters acetylcholine (ACh) and ATP and relaxing sphincters by releasing nitric oxide. ACh is the main transmitter released and smooth muscle contraction is mediated via a mixed M2/M3 receptor population M3 receptors acting via phospholipase C and M2 receptors acting via inhibition of adenylate cyclase. In ileal, colonic, gastric and bladder (detrusor) smooth muscle the density of M2 receptors is far greater than the density of M3 receptors, the M2:M3 ratio being 3:1 in most species including man. Despite the predominance of M2-receptors, direct contraction of intestinal and detrusor smooth muscle is mediated via the M3-receptor subtype and only this subtype is involved in contraction in vitro. Furthermore, knocking out the M3-receptor gene can have severe consequences on intestinal and bladder responses. In some tissues however M2-receptors may mediate an indirect "re-contraction" whereby a reduction in adenylate cyclase activity reverses the relaxation induced by beta-adrenoceptor stimulation. Thus, intestinal and bladder responses to muscarinic agonists are slightly depressed in M2 receptor knockout mice. The role of receptor subtypes in disease is unclear, but an enhancement of M2 receptor mediated responses has been reported to occur in diabetes. Animal models suggest that M2 receptors may play a greater role in some situations such as in the denervated bladder and intestine. In human disease the mechanisms operating are not so clear. Detrusor sensitivity to muscarinic agonists is enhanced in the neurogenic overactive bladder, but there is controversy surrounding the role of M2 receptors and conflicting results have been reported. Thus, the main muscarinic receptor mediating contraction in normal smooth muscle is the M3 receptor, but M2 receptors are also present and possibly may have an enhanced role in disease.
Publisher: Wiley
Date: 12-1994
DOI: 10.1111/J.1474-8673.1994.TB00618.X
Abstract: 1. The alpha 1-adrenoceptor-mediated responses of the rat urethra to phenylephrine have been examined in vitro. Phenylephrine caused concentration-dependent contractions of the isolated urethra which were antagonized by WB4101 (3-30 nM) and prazosin (10-100 nM) but not idazoxan (1.5 microM). Schild plot analysis of the antagonism by prazosin and WB4101 yielded straight lines with slopes not significantly different from unity. The pA2 value of 9.0 for WB4101 was significantly greater than the value previously obtained at the alpha 1B-adrenoceptor of the rat spleen. 2. 5-Methylurapidil (30 nM) and abanoquil (1 nM) caused dextral shifts of concentration-response curves yielding pKB values of 8.3 and 9.4 respectively. Maximal responses to phenylephrine were also reduced by this concentration of abanoquil. 3. Preincubation with chloroethylclonidine (25 microM for 40 min) failed to alter responses, but removing extracellular calcium or the presence of nifedipine (1 microM) almost abolished contractions to phenylephrine. 4. These results indicate that the responses of the rat urethra to phenylephrine are mediated via the alpha 1A-adrenoceptor subtype and are dependent on the influx of extracellular calcium.
Publisher: Springer Science and Business Media LLC
Date: 03-07-2007
DOI: 10.1007/S00210-007-0173-7
Abstract: The aim of this study was to demonstrate the presence of 5-HT(3) receptors in the mouse bladder and to determine their location. Bladder strips from female mice were set up in gassed Krebs-Henseleit solution at 37 degrees C and contractions recorded in response to electrical field stimulation (8 Hz, 60 V, 0.5-ms pulse duration) applied for 2 s every 50 s. The potentiating effects of 5-hydroxytryptamine (5-HT) were recorded (in the presence of 1-microM methysergide and 1-microM GR125487 to isolate the 5-HT(3) receptor response), and contractions were expressed as a percentage of the response to 0.1-M KCl. Responses to (5-HT) were also obtained in the presence of the 5-HT(3) receptor antagonist, ondansetron. RT-PCR was used to detect the expression of the 5-HT(3A) and 5-HT(3B) subunit transcripts of the mouse 5-HT(3) receptor. 5-HT and 5-HT(3) receptor agonists caused concentration-dependent increases in the force of neurogenic contractions without affecting the baseline tone. The rank order of potency was: meta-chloro-phenylbiguanide (m-CPB) = 5-HT > 2-methyl-5-HT (2m5-HT) = 1-phenylbiguanide (1-PBG). The respective pEC(50) values were: 6.42 +/- 0.2 = 5.95 +/- 0.19 > 5.35 +/- 0.12 = 5.14 +/- 0.13. m-CPB acted as a full agonist (E (max) = 40.65 +/- 3.81% KCl), but both 2m5-HT and 1-PBG acted as lower potency partial agonists. Ondansetron (30, 100, 300 nM) caused concentration-related rightward displacements to the concentration-effect curve to 5-HT. Nonlinear regression analysis of the effect of the ondansetron concentrations on the pEC(50) values produced a pK(B) value of 8.29 +/- 0.22. Desensitization of sensory nerves to the contractile effect of capsaicin (10 microM for 60 min) did not alter the ability of 5-HT to potentiate neurogenic contractions. 5-HT (3 microM) inhibited contractions induced by direct muscle stimulation (lignocaine, 300 microM and 10-ms pulse width). m-CPB also caused the same effect with a pIC(50) of 6.62 +/- 0.10 and an E (max) of 48.03 +/- 2.25%. The concentration-response curve to m-CPB was shifted rightwards by ondansetron (1 microM) giving an apparent pK(B) value of 8.15 +/- 0.33. mRNA for both the 5-HT(3A) and 5-HT(3B) receptor subunits was detected in the detrusor as well as the mucosa with a greater relative expression of the 5-HT(3A) subunit in both layers. This study demonstrates that 5-HT mediates enhanced neurogenic contractions of the mouse bladder muscle by an action at 5-HT(3) receptors located prejunctionally on nonsensory nerve elements. Additionally, an inhibitory postjunctional population of the 5-HT(3) receptor was identified. The presence of the 5-HT(3) receptor was confirmed by the expression of both 5-HT(3A) and 5-HT(3B) receptor subunits of the 5-HT(3) receptor.
Publisher: Springer Science and Business Media LLC
Date: 24-02-2015
DOI: 10.1038/NCOMMS7301
Abstract: The precise pathways of memory T-cell differentiation are incompletely understood. Here we exploit transgenic mice expressing fluorescent cell cycle indicators to longitudinally track the ision dynamics of in idual CD8 + T cells. During influenza virus infection in vivo , naive T cells enter a CD62L intermediate state of fast proliferation, which continues for at least nine generations. At the peak of the anti-viral immune response, a subpopulation of these cells markedly reduces their cycling speed and acquires a CD62L hi central memory cell phenotype. Construction of T-cell family ision trees in vitro reveals two patterns of proliferation dynamics. While cells initially ide rapidly with moderate stochastic variations of cycling times after each generation, a slow-cycling subpopulation displaying a CD62L hi memory phenotype appears after eight isions. Phenotype and cell cycle duration are inherited by the progeny of slow cyclers. We propose that memory precursors cell-intrinsically modulate their proliferative activity to ersify differentiation pathways.
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.EURURO.2009.12.030
Abstract: The main treatment for overactive bladder (OAB) is the use of anticholinergic drugs initially believed to inhibit the effect of parasympathetic acetylcholine (ACh) on the detrusor however, there is now evidence to suggest that anticholinergic drugs could interact with sensory pathways. Investigate the role of muscarinic receptors and ACh in modulating bladder afferent sensitivity in the mouse. Bladder and surrounding tissue were removed from wild-type male mice, placed in a recording chamber, and continually perfused with fresh oxygenated Krebs solution at 35 degrees C. Bladders were cannulated to allow infusion and intravesical pressure monitoring, and afferent nerve fibres innervating the bladder were dissected and put into a suction electrode for recording. Multiunit afferent activity and intravesical pressure were recorded at baseline and during bladder distension. Experiments were conducted in the presence of muscarinic agonists and antagonist or in the presence of the cholinesterase inhibitor physostigmine. Blocking muscarinic receptors using atropine (1 microM) had no effect on spontaneous afferent discharge, the afferent response to bladder distension, or on bladder compliance. However, stimulation of muscarinic receptors directly using bethanechol (100 microM) and carbachol (100 microM) or indirectly using physostigmine (10 microM) significantly inhibited the afferent response to bladder distension and concurrently reduced bladder compliance. Furthermore, prior application of nifedipine prevented the changes in bladder tone but did not prevent the attenuation of afferent responses by bethanechol or physostigmine. These data indicate that stimulation of muscarinic receptor pathways can depress sensory transduction by a mechanism independent of changes in bladder tone, suggesting that muscarinic receptor pathways and ACh could contribute to normal or pathologic bladder sensation.
Publisher: Springer Science and Business Media LLC
Date: 12-2003
DOI: 10.1007/S00210-003-0823-3
Abstract: The aim was to determine whether uptake of 5-hydroxytryptamine (5-HT) by the 5-HT transporter (SERT) modulates contractile responses to 5-HT in rat pulmonary arteries and whether this modulation is altered by exposure of rats to chronic hypoxia (10% oxygen 8 h/day 5 days). The effects of the SERT inhibitor, citalopram (100 nM), on contractions to 5-HT were determined in isolated ring preparations of pulmonary artery (intralobar and main) and compared with data obtained in systemic arteries. In intralobar pulmonary arteries citalopram produced a potentiation (viz. an increase in potency, pEC(50)) of 5-HT. The potentiation was endothelium-dependent in preparations from normoxic rats but endothelium-independent in preparations from hypoxic rats. In main pulmonary artery endothelium-independent potentiation was seen in preparations from hypoxic rats but no potentiation occurred in preparations from normoxic rats. In systemic arteries, citalopram caused endothelium-independent potentiation in aorta but no potentiation in mesenteric arteries there were no differences between hypoxic and normoxic rats. It is concluded that SERT can influence the concentration of 5-HT in the vicinity of the vasoconstrictor receptors in pulmonary arteries. The data suggest that in pulmonary arteries from hypoxic rats, unlike normoxic rats, the SERT responsible for this effect is not in the endothelium and, hence, is probably in the smooth muscle. The data are compatible with reports that, in the pulmonary circulation, hypoxia induces/up-regulates SERT, and hence increases 5-HT uptake, in vascular smooth muscle. The findings may have implications in relation to the suggested use of SERT inhibitors in the treatment of pulmonary hypertension.
Publisher: Wiley
Date: 23-03-2018
DOI: 10.1111/IMCB.12026
Abstract: Cutaneous immunity represents a crucial component of the mammalian immune response. The presence of a large array of commensal microorganisms along with a myriad of environmental stresses necessitates constant immuno-surveillance of the tissue. To achieve a perfect balance between immune-tolerance and immune-activation, the skin harbors strategically localized immune cell populations that modulate these responses. To maintain homeostasis, innate and adaptive immune cells assimilate microenvironmental cues and coordinate cellular and molecular functions in a spatiotemporal manner. The role of lymphoid cells in cutaneous immunity is gaining much appreciation due to their important roles in regulating skin health and pathology. In this review, we aim to highlight the recent advances in the field of cutaneous lymphoid biology.
Publisher: Wiley
Date: 2004
Publisher: Elsevier BV
Date: 09-2023
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2003
Publisher: Wiley
Date: 02-2003
Publisher: Elsevier BV
Date: 12-2011
DOI: 10.1016/J.UROLOGY.2011.08.039
Abstract: To investigate the effects of tissue stretch and muscarinic receptor stimulation on the spontaneous activity of the urothelium/lamina propria and identify the specific receptor subtype mediating these responses. Isolated strips of porcine urothelium with lamina propria were set up for in vitro recording of contractile activity. Muscarinic receptor subtype-selective antagonists were used to identify the receptors influencing the contractile rate responses to stretch and stimulation with carbachol. Isolated strips of urothelium with lamina propria developed spontaneous contractions (3.7 cycles/min) that were unaffected by tetrodotoxin, Nω-nitro-L-arginine, or indomethacin. Carbachol (1 μM) increased the spontaneous contractile rate of these tissue strips by 122% ± 27% (P < .001). These responses were significantly depressed in the presence of the M3-selective muscarinic antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (10-30 nM) but were not affected by the M1-selective antagonist pirenzepine (30-100 nM) or the M2-selective antagonist methoctramine (0.1-1 μM). Stretching of the tissue also caused an increase in the spontaneous contractile rate, and these responses were abolished by atropine (1 μM) and low concentrations of 4-diphenylacetoxy-N-methylpiperidine methiodide (10 nM). Darifenacin, oxybutynin, tolterodine, and solifenacin (1 μM) all significantly depressed the frequency responses to carbachol (1 μM). The urothelium with the lamina propria exhibits a spontaneous contractile activity that is increased during stretch. The mechanism appears to involve endogenous acetylcholine release acting on M3 muscarinic receptors. Anticholinergic drugs used clinically depress the responses of these tissues, and this mechanism might represent an additional site of action for these drugs in the treatment of bladder overactivity.
Publisher: The Korean Society of Neurogastroenterology and Motility
Date: 30-12-2015
DOI: 10.5056/JNM15036
Publisher: Wiley
Date: 06-2000
DOI: 10.1046/J.1365-2680.2000.00181.X
Abstract: 1. The objective of the study was to determine the role of muscarinic receptor subtypes in mediating contraction of the porcine detrusor smooth muscle in vitro. 2. Strips of pig detrusor muscle were set up in physiological salt solution and the tensions developed by the tissues were recorded. Responses to carbachol were obtained in the absence and presence of a range of muscarinic antagonists (4-DAMP, methoctramine, darifenacin, oxybutynin, tolterodine and pirenzepine). Antagonist affinity values (pKB values) were calculated and compared with those quoted in the literature for these antagonists at each of the muscarinic receptor subtypes. 3. The M3-selective antagonists, 4-DAMP and darifenacin had high affinities (pKB values of 9.4 and 8.6, respectively). Oxybutynin, tolterodine and pirenzepine had affinities of 8.2, 8.1 and 6.8, respectively, whilst the M2-selective agent methoctramine had a relatively low affinity (pKB = 6.1). The rank order of affinities was, therefore, 4-DAMP > darifenacin > oxybutynin > tolterodine > pirenzepine > methoctramine for the pig detrusor. Correlation of the antagonist affinities obtained on the bladder with those published for these antagonists at the five muscarinic receptor subtypes identified the M3(m3)-receptor as the muscarinic subtype mediating detrusor contractile responses in vitro. 4. These data suggest that a small population of M3-muscarinic receptors must mediate direct contractile responses of the pig detrusor muscle to muscarinic receptor stimulation in vitro.
Publisher: Wiley
Date: 20-02-2004
DOI: 10.1111/J.1464-410X.2003.04681.X
Abstract: To compare the serotonin (5-HT)4-receptor-mediated effects of 5-HT on the potentiation of cholinergic responses to electrical-field stimulation (EFS) in isolated strips of detrusor muscle from patients with normal or neurogenic overactive bladders. Strips of detrusor muscle were field-stimulated (10 Hz, 0.01 ms duration, 60 V for 5 s) at 100-s intervals until consistent responses were obtained. In the presence of methiothepin, ketanserin and ondansetron (all 1 mumol/L) to block 5-HT1, 5-HT2 and 5-HT3 receptors, respectively, the cumulative administration of 5-HT or the selective 5-HT4 agonist cisapride, produced concentration-dependent enhancement of responses to EFS in both types of tissue. The maximum potentiation induced by 5-HT in neurogenic overactive detrusor muscle was reduced (P < 0.05) by about half compared to normal detrusor muscle, but EC50 values obtained in normal and overactive tissue were not significantly different. Cisapride was less potent than 5-HT and acted as a partial agonist relative to 5-HT. The selective 5-HT4 receptor antagonist RS-100235 was a potent antagonist of the 5-HT-induced potentiation of responses to EFS. At 3 nmol/L RS-100235 antagonized the effects of 5-HT in both groups of tissues without affecting the maximum responses. The affinity estimates (apparent pKB values of 9.2-9.5) for this antagonist were similar in normal and overactive detrusor muscle. These results indicate that 5-HT4 receptor-mediated potentiation of field-stimulated responses is lower in the neurogenic overactive detrusor muscle than in normal tissue. 5-HT4 receptor antagonist affinity is unchanged in the neurogenic overactive bladder.
Publisher: Elsevier BV
Date: 04-2010
DOI: 10.1016/J.PUPT.2009.10.013
Abstract: The aim of the present study was to establish whether polymorphisms, especially those within the promoter region, of the beta(2)-adrenoceptor gene (ADRB2) influence beta(2)-adrenoceptor expression in human lung. The density of beta-adrenoceptors in human lung tissue (n=88) was determined by saturation binding using the radioligand, iodinated cyanopindolol. Discrimination of beta(1)- and beta(2)-adrenoceptors was determined using the highly selective beta(1)-adrenoceptor antagonist, CGP20712A. Genotype was determined at 5 positions of ADRB2 previously reported as polymorphic. Potential influences of single nucleotide polymorphisms (SNPs) within the promoter region (-367, -47) and coding block (46, 79, 491) of ADRB2 on beta(2)-adrenoceptor expression were investigated. The density of beta(2)-adrenoceptors was variable among the 88 lung preparations studied ranging from 17 to 177fmol/mg protein (mean+/-S.E.M., 72+/-4fmol/mg protein). There was no influence of genotype on beta(2)-adrenoceptor expression for any of the polymorphisms studied except at position 491. The polymorphism at position 491C>T, leading to a change from thr to ile at amino acid 164, is uncommon. Preparations genotyped as heterozygous (126+/-15fmol/mg protein n=5) expressed significantly (P=0.0005) higher levels of beta(2)-adrenoceptor than those that were homozygous (69+/-4fmol/mg protein n=83). With the exception of position 491, these data indicate that polymorphisms of ADRB2 do not influence beta(2)-adrenoceptor expression in human lung.
Publisher: S. Karger AG
Date: 2002
DOI: 10.1159/000063815
Abstract: i Background: /i Active and significant relaxation of the human gallbladder must be one of the facets of its motility during both the filling and emptying cycle. Conflicting reports about the presence or significance of nitric oxide have been reported in the literature. The aim of this study was to investigate the role of nitric oxide and K sub ATP /sub channels in human gallbladder muscle using isolated strips from human gallbladder. i Methods: /i Full thickness strips were obtained from 56 human gallbladders and suspended under isometric tension in organ baths. The effect of nitric oxide donors and inhibitors on cholecystokinin octapeptide- and carbachol-induced contraction was examined. In separate experiments the effect of the K sub ATP /sub channel activator, cromakalim, and the inhibitor, glibenclamide, were determined. i Results: /i Cromakalim induced a significant relaxation of agonist-induced contraction in human gallbladder in vitro, an effect which was abolished by the K sub ATP /sub channel inhibitor glibenclamide. No evidence of significant nitric oxide involvement in relaxation was observed. i Conclusions: /i This study has demonstrated the presence of K sub ATP /sub channels in human gallbladder for the first time. These are capable of causing significant relaxation in the presence of hormonal and muscarinic agonists and may represent a major pathway for gallbladder relaxation.
Publisher: Wiley
Date: 04-1986
DOI: 10.1113/JPHYSIOL.1986.SP016053
Abstract: Chemical sympathectomy of guinea-pigs was induced by chronic pretreatment with 6-hydroxydopamine over a 20 day period. Control animals were sham injected with vehicle at the same times. Isolated tissues were removed from the animals and beta-adrenoceptor sensitivity assessed from cumulative concentration-response curves for isoprenaline, followed after wash-out by a partial agonist (salbutamol, ritodrine or prenalterol). The following responses were measured: increases in force and rate of contraction of left and right atria respectively, inhibition of carbachol-induced ileal contractions, relaxation of intrinsic tone of lung strips and tracheal spirals, inhibition of contractions of vas deferens and soleus muscle induced by field stimulation. Left and right atria and ileum from 6-hydroxydopamine-pretreated guinea-pigs exhibited supersensitivity to beta-adrenoceptor stimulation. This was measured as a leftwards shift of the concentration-response curve for isoprenaline and as an elevation of the partial agonist maximum response (relative to isoprenaline), when compared with tissues from sham-injected controls. The supersensitivity was assumed to be due to the loss of endogenous neurotransmitter release by chemical sympathectomy and specific for the beta-adrenoceptor. In contrast, lung strips, vas deferens and soleus muscle were not supersensitive. The responses of these tissues are thought to be mediated via beta 2-adrenoceptors whereas cardiac and ileal responses are beta 1-adrenoceptor mediated. The latter receptor subtype would therefore appear to be under the influence of sympathetic innervation, but since no supersensitivity occurred at beta 2-adrenoceptors these were presumed to be non-innervated but stimulated by circulating adrenaline. These results obtained by use of chemical sympathectomy with 6-hydroxydopamine support the contention that the physiological basis of beta-adrenoceptor subclassification is that the beta 1-subtype are innervated whereas the beta 2-subtype are non-innervated.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2016
Publisher: Springer Science and Business Media LLC
Date: 21-04-2022
DOI: 10.1007/S00210-022-02244-0
Abstract: The β 3 -agonist mirabegron is thought to induce relaxation of the detrusor muscle, contributing to the improvement of overactive bladder symptoms. There has been recent interest in purposing mirabegron as a medical expulsive therapy drug to improve the passage of smaller kidney stones by relaxing the ureteral smooth muscles. The aim of this study was to determine the effects of mirabegron on the activity of the ureter. Additionally, we investigated the receptor and mechanisms through which mirabegron exerts these effects. In vitro agonist-induced responses of isolated porcine distal ureteral tissues were measured in the absence and presence of mirabegron in organ bath experiments. The responses were expressed as frequency, area under the curve and maximum litude. Mirabegron at concentrations of 100 nM and lower failed to suppress phenylephrine- or 5-HT-induced contractions in the porcine ureteral strip. Mirabegron at 1 μM and 10 μM produced a rightward shift of phenylephrine concentration–response curves in these tissues. This effect of mirabegron (10 μM) was not present in 5-HT concentration–response curves. The mirabegron effect on phenylephrine-induced contractions was also not abolished by β-adrenoceptor antagonist SR 59230A (10 μM), β-adrenoceptor antagonist propranolol (10 μM), α 2 -adrenoceptor antagonist yohimbine (30 nM), and nitric oxide synthase inhibitor l -NNA (10 μM). The present results show that mirabegron suppresses ureteral contractile responses in the porcine ureter via α 1 -adrenoceptor antagonism, since their effects were not present when the tissues were contracted with 5-HT. Furthermore, the inhibitory effects by mirabegron were not affected by β 3 -adrenoceptor antagonists.
Publisher: Wiley
Date: 05-2000
DOI: 10.1046/J.1464-410X.2000.00573.X
Abstract: To investigate the presence of functional neuropeptide Y (NPY) receptors in human bladder and prostate (both richly endowed with NPY-containing nerve fibers) using peptide YY (PYY) as the agonist. Materials and methods Binding studies were conducted using [125I]PYY as the radioligand. Organ-bath studies were performed on isolated tissue strips for direct (postjunctional) contractile effects and for (prejunctional) inhibition of field stimulation effects. Any possible degradation of PYY was determined using high-performance liquid chromatography (HPLC). In the radioligand binding studies no quantifiable specific [125I]PYY binding was detected in human bladder or prostate, while specific high-affinity binding was readily seen in rat cerebral cortex. In organ-bath experiments, PYY (up to 1 micromol/L) caused no contraction of human prostate or bladder, whereas noradrenaline and carbachol, respectively, were effective the potency or efficacy of noradrenaline and carbachol were not altered by PYY. Field stimulation-induced contraction was not affected by PYY in either human bladder or prostate, but was readily inhibited in rat vas deferens. HPLC detected no relevant PYY degradation by human bladder or prostate homogenates. Human bladder and prostate express only very few if any functional NPY receptors.
Publisher: Wiley
Date: 16-08-2016
DOI: 10.1111/IJU.13172
Abstract: To examine the effect of 5-hydroxytryptamine (5-HT serotonin) on the contractile properties of the urothelium and lamina propria, as a better understanding of bladder physiology might aid the development of new treatments. Strips of porcine urothelium and lamina propria were suspended in gassed Krebs-bicarbonate solution, and cumulative concentration-response curves for 5-HT were generated in the absence and presence of 5-HT antagonists, Nω-nitro-l-arginine and indomethacin. Responses to α-methyl-5-HT were also examined. Strips of urothelium/lamina propria developed spontaneous contractions, whereas the addition of 5-HT induced concentration-dependent increases in contractile tone with maximal contractions of 50.43 ± 2.78 mN/g tissue weight (n = 100). Tonic contractions to 5-HT were unchanged in the presence of Nω-nitro-l-arginine (100 μmol/L) or indomethacin (5 μmol/L). Selective concentrations of the antagonists methiothepin (5-HT The results show that contractile responses of the urothelium/lamina propria to 5-HT are predominantly mediated through the 5-HT
Publisher: Wiley
Date: 09-2008
DOI: 10.1038/BJP.2008.217
Publisher: Springer Science and Business Media LLC
Date: 09-2021
DOI: 10.1038/S41598-021-97053-5
Abstract: Psychological stress has been linked to the development and exacerbation of overactive bladder symptoms, as well as afferent sensitisation in other organ systems. Therefore, we aimed to investigate the effects of water avoidance stress on bladder afferent nerve activity in response to bladder filling and pharmaceutical stimulation with carbachol and ATP in mice. Adult female C57BL/6J mice were exposed to either water avoidance stress (WAS) for 1 h/day for 10 days or normal housing conditions. Voiding behaviour was measured before starting and 24-h after final stress exposure and then animals were euthanised to measure afferent nerve activity in association with bladder compliance, spontaneous phasic activity, contractile responses, as well as release of urothelial mediators. WAS caused increased urinary frequency without affecting urine production. The afferent nerve activity at low bladder pressures (4–7 mmHg), relevant to normal physiological filling, was significantly increased after stress. Both low and high threshold nerves demonstrated enhanced activity at physiological bladder pressures. Urothelial ATP and acetylcholine release and bladder compliance were unaffected by stress as was the detrusor response to ATP (1 mM) and carbachol (1 µM). WAS caused enhanced activity of in idual afferent nerve fibres in response bladder distension. The enhanced activity was seen in both low and high threshold nerves suggesting that stressed animals may experience enhanced bladder filling sensations at lower bladder volumes as well as increased pain sensations, both potentially contributing to the increased urinary frequency seen after stress.
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.EJPHAR.2011.11.020
Abstract: In the bladder, nitric oxide (NO) is released from neuronal and non-neuronal sources, but its actions are unclear. Strips of urothelium plus lamina propria contract in response to agonists and develop spontaneous phasic contractions, and the aim of this study was to investigate the influence of NO on this activity. Isolated strips of urothelium/lamina propria from porcine bladder developed spontaneous contractions (3.5 ± 0.3 cycles/min) and contracted in response to carbachol and electrical field stimulation (EFS). The NO synthase inhibitor N(ω)-nitro-l-arginine (L-NNA, 100 μM) had no effects on the tissues, but the NO donors diethylamine NONOate (DEANO, 100 μM) and nitroprusside (10 μM) caused relaxation, slowed the spontaneous rate of contractions and inhibited responses to carbachol. Maximum tonic contractions to carbachol were reduced by 17 ± 4% (P<0.001) and 35 ± 5% (P<0.001) by DEANO and nitroprusside respectively and the potency of carbachol was also reduced. Carbachol also increased the spontaneous frequency of contraction and these rate responses were again inhibited by DEANO and nitroprusside, but unaffected by L-NNA. Similarly, responses to EFS were significantly depressed (52-70%) by DEANO (P<0.05), but were unaffected by L-NNA. These data demonstrate spontaneous contractile activity and also nerve and agonist-induced tonic contractile activity within the urothelium and lamina propria. This activity is sensitive to depression by NO, but NO does not appear to be spontaneously released to influence this activity, nor does it appear to be released by muscarinic receptor stimulation. However the results suggest that in situations where NO production is increased, NO can influence the contractile activity of this tissue.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 21-05-2018
Abstract: Inflammation may play a causal role in urological side effects reported following intravesical mitomycin C (MMC). Our aim was to investigate the effects of the nonsteroidal anti-inflammatory drug ibuprofen (IBU) on the cytotoxic potency of MMC and the potential for IBU to protect against bladder dysfunction. Malignant (RT4, T24) and normal (UROtsa) urothelial lines were treated with MMC followed by ibuprofen, with cell viability and caspase-3 activity assessed. Female C57BL/6JArc mice (Saline/Control, MMC, Saline + IBU, and MMC + IBU) received intravesical treatment (1 hour) with saline or MMC (2 mg/ml), with IBU (1 mg/ml) delivered in drinking water (for 7 days). Voiding pattern analysis was conducted prior to and following (1, 3, 7 days) treatment. A whole-bladder preparation was used to assess compliance, contractile responses, and urothelial-mediator release. Ibuprofen selectively increased the cytotoxic potency of MMC and caspase-3 activity in both malignant cells lines but not in UROtsa. MMC significantly increased voiding frequency at 24 hours and 3 days, whereas administration of ibuprofen significantly reduced this effect. MMC significantly increased the frequency of spontaneous contractions from 2.3 ± 0.5 contractions/min in saline controls to 4.8 ± 0.16 contractions/min, with ibuprofen protecting against this change. Interestingly, although nerve-evoked responses were not altered by MMC, they were increased in both IBU groups. Ibuprofen improved voiding dysfunction following MMC treatment by reducing spontaneous phasic activity and enhancing nerve-mediated contractions. Ibuprofen use in bladder cancer patients may help to minimize the urological adverse effects associated with intravesical MMC.
Publisher: Springer Science and Business Media LLC
Date: 07-03-2019
DOI: 10.1038/S41598-019-40384-1
Abstract: The mechanisms underlying bladder contractile disorders such as overactive bladder are not fully understood, and there is limited understanding of the receptor systems modulating spontaneous bladder contractions. We investigated the potential for histamine to have a role in mediating contractility of the urothelium with lamina propria (U& LP) or detrusor via the H1-H4 histamine receptor subtypes. Isolated strips of porcine U& LP or detrusor smooth muscle were mounted in gassed Krebs-bicarbonate solution and responses to histamine obtained in the absence and presence of selective receptor antagonists. The presence of histamine increases the frequency of U& LP spontaneous phasic contractions and baseline tensions. In response to histamine, H1-antagonists pyrilamine, fexofenadine and cyproheptadine were effective at inhibiting contractile responses. Cimetidine (H2-antagonist) enhanced increases in baseline tension in response histamine, whereas amthamine (H2-agonist) induced relaxation. Although thioperamide (H3/H4-antagonist) increased baseline tension responses to histamine, selective H1/H2-receptor antagonism revealed no influence of these receptors. In detrusor preparations, pyrilamine, fexofenadine and cyproheptadine were effective at inhibiting baseline tension increases in response to histamine. Our findings provide evidence that histamine produces contractile responses both in the U& LP and detrusor via the H1-receptor, and this response is significantly inhibited by activation of the H2-receptor in the U& LP but not the detrusor.
Publisher: Oxford University Press (OUP)
Date: 05-1994
DOI: 10.1111/J.2042-7158.1994.TB03806.X
Abstract: This study demonstrates that in-vitro incubation with insulin results in a reduction of the sensitivity of cardiac tissues from streptozotocin-diabetic rats to isoprenaline. Following incubation with insulin, the sensitivity of left atria and papillary muscles from diabetic animals was not significantly different from those of control animals. Insulin incubation had no effect on the sensitivity of diabetic tissues to forskolin or on ventricular β-adrenoceptor number. Reduction of blood glucose in the absence of insulin by fasting, did not affect the sensitivity of tissues from diabetic animals to isoprenaline. These results suggest that insulin itself can directly reduce β-adrenoceptor sensitivity without altering receptor number.
Publisher: Wiley
Date: 08-1998
DOI: 10.1002/(SICI)1098-2299(199808)44:4<140::AID-DDR2>3.0.CO;2-R
Publisher: Wiley
Date: 02-01-1990
DOI: 10.1111/J.1472-8206.1990.TB01014.X
Abstract: Phenylephrine produced concentration-related positive inotropic responses in isolated left atria and papillary muscles of guinea-pigs and rats. In rat tissues, these responses were unaffected by propranolol but antagonized by prazosin and therefore mediated via alpha 1-adrenoceptors. The alpha 1-adrenoceptor agonist methoxamine also exerted positive inotropic effects in these rat tissues. The maximum alpha-adrenoceptor-mediated effect of methoxamine (relative to the isoprenaline maximum) was greater than that of phenylephrine in left atria (in the presence of propranolol), whereas in papillary muscles phenylephrine exerted the greater maximum. In guinea-pig papillary muscles, the response to phenylephrine was unaffected by prazosin but was antagonized by propranolol and therefore caused by stimulation of beta-adrenoceptors. Methoxamine had no effect in guinea-pig papillary muscles. Guinea-pig left atria produced biphasic concentration-response curves for phenylephrine, the lower portion being antagonized by phentolamine and was therefore alpha-adrenoceptor-mediated, while the upper portion was antagonized by propranolol and therefore beta-adrenoceptor-mediated. Methoxamine exerted a small inotropic response, the maximum of which was similar to that of the first component of the phenylephrine response. Phenylephrine was a partial agonist for the cardiac beta-adrenoceptor. The density of rat ventricular alpha-adrenoceptors was 4 times greater than beta-adrenoceptor density, as measured by [3H]-prazosin and [3H]-dihydroalprenolol binding. This explains why the responses of rat papillary muscles were alpha-adrenoceptor-mediated. In contrast, the density of beta-adrenoceptor binding sites in guinea-pig ventricles was 6 times greater than the alpha-adrenoceptor density. This explains why the phenylephrine responses were beta-adrenoceptor-mediated in guinea-pig papillary muscles. In the left atria of guinea-pigs, which displayed both alpha- and beta-adrenoceptor-mediated responses, the densities of alpha- and beta-adrenoceptor binding sites were similar. Thus, phenylephrine exerts positive inotropic effects through alpha- or beta-adrenoceptors depending upon their relative densities.
Publisher: Springer Science and Business Media LLC
Date: 28-02-2023
DOI: 10.1007/S11884-023-00690-X
Abstract: To examine the latest published findings on the pathophysiological mechanisms involved in the development of overactive bladder (OAB) and detrusor overactivity (DO), and to identify common pathways linked to the risk factors associated with these conditions. Evidence is accumulating, both clinical and experimental, that many of the factors linked to the development of OAB/DO, including ageing, bladder outlet obstruction, psychological stress, and obesity are associated with reduced bladder blood flow. This induces local tissue inflammation with cytokine release and enhanced oxidative stress, ultimately resulting in altered detrusor sensitivity, detrusor hypertrophy and fibrosis, together with afferent hypersensitivity. These mechanisms would explain the symptoms of urgency and frequency observed in OAB patients. Although not a characteristic of OAB, undetected low level bacterial infections of the bladder have been proposed to explain the OAB symptoms in patients resistant to standard treatments. In this condition, inflammatory responses without reductions in perfusion activate the inflammatory pathways. Evidence is mounting that poor bladder perfusion and local inflammatory responses are central mechanisms involved in the development of OAB/DO. As our understanding of these pathophysiological mechanisms advances, new avenues for drug development will be identified and ultimately treatment may become more in idualized depending on the particular pathway involved and the drugs available.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2007
DOI: 10.1016/J.JURO.2007.05.116
Abstract: We established the level of adenosine triphosphate release by the urothelium in patients with painful bladder syndrome and compared it with that from the normal human bladder. Biopsies of urothelium from patients with painful bladder syndrome were subjected to stretch by 130% and 150% of the original length, and 10 Hz electric stimulation. A luciferase assay was used to quantify adenosine triphosphate release. The neurotoxin tetrodotoxin was used to block the neuronal source of adenosine triphosphate release. There was a significantly greater release of adenosine triphosphate following mechanical stretch of the urothelium from painful vs control bladders. The increase in adenosine triphosphate release in painful vs control bladders was statistically significant whether expressed in absolute values (mean +/- SE 3,791.4 +/- 667.9 vs 77.6 +/- 16.2 pM gm(-1) tissue) or as an increase over baseline (282.2% +/- 24.8% vs 175.4% +/- 21.7%). Similarly there was a significant release of adenosine triphosphate following electrical field stimulation of the urothelium from painful vs control bladders (1,348.6 +/- 278.2 vs 61.7 +/- 10.1 pM gm(-1) tissue, p <0.005), representing a 278% +/- 41.5% vs 137.9% +/- 4.4% increase above baseline (p <0.005). The source of adenosine triphosphate release was nonneuronal in 89% of painful bladders and in 84% of control bladders. There is a significantly increased level of adenosine triphosphate release from the urothelium of painful bladders in comparison to that from normal bladders, suggesting an important potential functional role for adenosine triphosphate in this condition.
Publisher: Hindawi Limited
Date: 2014
DOI: 10.1155/2014/347616
Abstract: DMSO is used as a treatment for interstitial cystitis and this study examined the effects of luminal DMSO treatment on bladder function and histology. Porcine bladder was incubated without (controls) or with DMSO (50%) applied to the luminal surface and the release of ATP, acetylcholine, and LDH assessed during incubation and in tissues strips after DMSO incubation. Luminally applied DMSO caused ATP, Ach, and LDH release from the urothelial surface during treatment, with loss of urothelial layers also evident histologically. In strips of urothelium/lamina propria from DMSO pretreated bladders the release of both ATP and Ach was depressed, while contractile responses to carbachol were enhanced. Detrusor muscle contractile responses to carbachol were not affected by DMSO pretreatment, but neurogenic responses to electrical field stimulation were enhanced. The presence of an intact urothelium/lamina propria inhibited detrusor contraction to carbachol by 53% and this inhibition was significantly reduced in DMSO pretreated tissues. Detection of LDH in the treatment medium suggests that DMSO permeabilised urothelial membranes causing leakage of cytosolic contents including ATP and Ach rather than enhancing release of these mediators. The increase in contractile response and high levels of ATP are consistent with initial flare up in IC/PBS symptoms after DMSO treatment.
Publisher: Wiley
Date: 12-2000
Publisher: Springer Science and Business Media LLC
Date: 17-02-2015
DOI: 10.1007/S00210-015-1097-2
Abstract: Intravesical administration of the cytotoxic drug doxorubicin is a common treatment for superficial carcinoma of the bladder, but it is associated with significant urological adverse effects. The aim of this study was to identify doxorubicin-induced changes in the local mechanisms involved in regulating bladder function. As a model of intravesical doxorubicin administration in patients, doxorubicin (1 mg/mL) was applied to the luminal surface of porcine bladders for 60 min. Following treatment, the release of urothelial/lamina propria mediators (acetylcholine (Ach), ATP and prostaglandin E2 (PGE2) and contractile responses of isolated tissue strips was investigated. Doxorubicin pretreatment did not affect contractile responses of detrusor muscle to carbachol, but did enhance neurogenic detrusor responses to electrical field stimulation (219 % at 5 Hz). Contractions of isolated strips of urothelium/lamina propria to carbachol were also enhanced (30 %) in tissues from doxorubicin pretreated bladders. Isolated strips of urothelium/lamina propria from control bladders demonstrated a basal release of all three mediators (Ach > ATP > PGE2), with increased release of ATP when tissues were stretched. In tissues from doxorubicin-pretreated bladders, the basal release of ATP was significantly enhanced (sevenfold), while the release of acetylcholine and PGE2 was not affected. The application of luminal doxorubicin, under conditions that mimic intravesical administration to patients, affects urothelial/lamina propria function (increased contractile activity and ATP release) and enhances efferent neurotransmission without affecting detrusor smooth muscle. These actions would enhance bladder contractile activity and sensory nerve activity and may explain the adverse urological effects observed in patients following intravesical doxorubicin treatment.
Publisher: Springer Berlin Heidelberg
Date: 03-11-2011
DOI: 10.1007/978-3-642-23274-9_16
Abstract: Voiding of the bladder is the result of a parasympathetic muscarinic receptor activation of the detrusor smooth muscle. However, the maintenance of continence and a normal bladder micturition cycle involves a complex interaction of cholinergic, adrenergic, nitrergic and peptidergic systems that is currently little understood. The cholinergic component of bladder control involves two systems, acetylcholine (ACh) released from parasympathetic nerves and ACh from non-neuronal cells within the urothelium. The actions of ACh on the bladder depend on the presence of muscarinic receptors that are located on the detrusor smooth muscle, where they cause direct (M₃) and indirect (M₂) contraction pre-junctional nerve terminals where they increase (M₁) or decrease (M₄) the release of ACh and noradrenaline (NA) sensory nerves where they influence afferent nerve activity umbrella cells in the urothelium where they stimulate the release of ATP and NO suburothelial interstitial cells with unknown function and finally, other unidentified sites in the urothelium from where prostaglandins and inhibitory/relaxatory factors are released. Thus, the actions of muscarinic receptor agonists and antagonists on the bladder may be very complex even when considering only local muscarinic actions. Clinically, muscarinic antagonists remain the mainstay of treatment for the overactive bladder (OAB), while muscarinic agonists have been used to treat hypoactive bladder. The antagonists are effective in treating OAB, but their precise mechanisms and sites of action (detrusor, urothelium, and nerves) have yet to be established. Potentially more selective agents may be developed when the cholinergic systems within the bladder are more fully understood.
Publisher: Wiley
Date: 10-1994
DOI: 10.1111/J.1476-5381.1994.TB17028.X
Abstract: 1. The responses of rat isolated aortae to vasoconstrictor and vasodilator agents have been studied in 14-day streptozotocin-diabetic rats. The effects of treatment with the aldose reductase inhibitor, ponalrestat, on these responses have also been investigated. 2. Maximum contractile responses and aortic sensitivity to phenylephrine were significantly enhanced in 14-day diabetic aortae. 3. In contrast, endothelium-dependent relaxations to carbachol were depressed in diabetic rats, whilst endothelium-independent relaxations to forskolin and sodium nitroprusside were unchanged. 4. Pretreatment with ponalrestat (25 mg kg-1, daily) prevented both the enhanced maximum contractile responses to phenylephrine and the depressed endothelium-dependent relaxations to carbachol in aortae from 14-day diabetic rats. Ponalrestat however, had no effect on the reduced phenylephrine EC50 values observed in tissues from diabetic animals. 5. It is concluded that ponalrestat prevents the depression of endothelium-dependent aortic relaxations induced by diabetes of 14 days duration, suggesting that the polyol pathway is involved in these vascular changes. Ponalrestat does not prevent the increase in aortic sensitivity to alpha 1-adrenoceptor agonists.
Publisher: Springer Science and Business Media LLC
Date: 31-05-2015
DOI: 10.1007/S00210-015-1137-Y
Abstract: Bladder dysfunction is common in the general population (Stewart et al. 2010) and even more so among patients seeing a physician for any reason (Goepel et al. 2002). It often manifests as lower urinary tract symptoms (LUTS), a term originally coined to describe voiding and storage symptoms in men with benign prostatic hyperplasia (BPH) but now more universally used to describe any type of voiding and storage symptoms in both sexes. Studies into possible causes of urinary bladder dysfunction have long focused on detrusor smooth muscle cells (Turner and Brading 1999). More recently, it became clear that several other types of cells and organs contribute to regulating detrusor smooth muscle function. These include the urothelium (Andersson and McCloskey 2014 Michel 2015), afferent nerves (Michel and Igawa 2015 Yoshimura et al. 2014b), and the central and autonomic nervous systems (Fowler and Griffiths 2010 Yoshimura et al. 2014a). Alterations in any of these may at least partly be responsible for detrusor dysfunction and, accordingly, be potential targets for the treatment of bladder dysfunction. As highlighted by an article in this issue of Naunyn-Schmiedeberg's Archives of Pharmacology (Bayrak et al. 2015), there is an additional suspect, the bladder vasculature. This article will discuss the currently available experimental and clinical evidence for a role of the vasculature in causing bladder dysfunction, and how existing and emerging treatments may modulate bladder function by acting on blood vessels. Due to a similarity in concept, data on prostate perfusion will also be discussed to some extent.
Publisher: Wiley
Date: 02-2000
DOI: 10.1046/J.1365-2680.2000.00155.X
Abstract: 1. The present study investigates the effect of treatment of 14-day streptozotocin-diabetic rats with the aldose reductase inhibitor, sorbinil, on changes ex vivo in aortic vasoconstriction and vasodilation. 2. Maximum contractile responses and aortic sensitivity to phenylephrine were significantly enhanced in aortae from 14-day diabetic rats, in accordance with our previous data. 3. Endothelium-dependent relaxations to carbachol were, in contrast, depressed, although endothelium-independent relaxations to forskolin and sodium nitroprusside were unaltered. 4. Sorbinil treatment of diabetic animals failed to prevent any of these diabetes-induced alterations in aortic function, and indeed exacerbated some of these alterations. In addition, sorbinil treatment caused altered aortic responses in control animals, which sometimes mirrored those found in diabetic animals. 5. It can be concluded that sorbinil may have actions in addition to, and independent of, polyol pathway inhibition. Thus, sorbinil may not be an effective tool for the investigation of aldose reductase inhibition within the vascular system of the rat.
Publisher: Springer Science and Business Media LLC
Date: 11-2001
Abstract: Antimuscarinic agents are the most widely used therapy for urge incontinence, but have side effects such as constipation, tachycardia and dry mouth, resulting from a lack of selectivity for the bladder. M2 receptors are the predominant cholinoceptors present in urinary bladder, but mainly the minor population of M3 receptors mediate its contraction. M2 receptors modulate detrusor contraction by several mechanisms, and may contribute more to contraction of the bladder in pathological states such as bladder denervation or spinal cord injury. Prejunctional inhibitory M2 or M4 receptors and prejunctional facilitatory muscarinic Ml receptors in the bladder have all been reported. In clinical studies, tolterodine, a non-selective muscarinic antagonist, has been reported to be as effective as oxybutynin but inducing less dry mouth. Thus, although it is not certain which antimuscarinic drugs have the better efficacy and tolerability, the non-selective antimuscarinic drugs seem to be better than M3-selective antagonists in their clinical efficacies. However, controlled release, or intravesical, intravaginal, or rectal administrations of oxybutynin have been reported to cause fewer side effects. Darifenacin, a new M3 selective antagonist, has been reported to have selectivity for the bladder over the salivary gland in vivo. To verify which antimuscarinic drugs selective for the muscarinic subtypes have the best efficacy and tolerability, comparative clinical trials between M3 selective antagonists and non-selective compounds, such as olterodine, are required in the future.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 10-2002
Abstract: Alterations in the myogenic activity of the bladder smooth muscle are thought to serve as a basis for the involuntary detrusor contractions associated with the overactive bladder. Activation of ATP-sensitive K(+) (K(ATP)) channels has been recognized as a potentially viable mechanism to modulate membrane excitability in bladder smooth muscle. In this study, we describe the preclinical pharmacology of (-)-(9S)-9-(3-bromo-4-fluorophenyl)-2,3,5,6,7,9-hexahydrothieno[3,2-b]quinolin-8(4H)-one 1,1-dioxide (A-278637), a novel 1,4-dihydropyridine K(ATP) channel opener (KCO) that demonstrates enhanced bladder selectivity for the suppression of unstable bladder contractions in vivo relative to other reference KCOs. A-278637 activated K(ATP) channels in bladder smooth muscle cells in a glyburide (glibenclamide)-sensitive manner as assessed by fluorescence membrane potential assays using bis-(1,3-dibutylbarbituric acid)trimethine oxonol (EC(50) = 102 nM) and by whole cell patch cl . Spontaneous (myogenic) phasic activity of pig bladder strips was suppressed (IC(50) = 23 nM) in a glyburide-sensitive manner by A-278637. A-278637 also inhibited carbachol- and electrical field-stimulated contractions of bladder strips, although the respective potencies were 8- and 13-fold lower compared with inhibition of spontaneous phasic activity. As shown in the accompanying article [Brune ME, Fey TA, Brioni JD, Sullivan JP, Williams M, Carroll WA, Coghlan MJ, and Gopalakrishnan M (2002) J Pharmacol Exp Ther 303:387-394], A-278637 suppressed myogenic contractions in vivo in a model of bladder instability with superior selectivity compared with other KCOs, WAY-133537 [(R)-4-[3,4-dioxo-2-(1,2,2-trimethyl-propylamino)cyclobut-1-enylamino]-3-ethyl-benzonitrile] and ZD6169 [(S)-N-(4-benzoylphenyl)3,3,3-trifluro-2hydroxy-2-methyl-priopionamide]. A-278637 did not interact with other ion channels, including L-type calcium channels or other neurotransmitter receptor systems. The pharmacological profile of A-278637 represents an attractive basis for further investigations of selective K(ATP) channel openers for the treatment of overactive bladder via myogenic etiology.
Publisher: Wiley
Date: 09-1985
DOI: 10.1111/J.1474-8673.1985.TB00124.X
Abstract: The positive inotropic responses of left atria and papillary muscles and the positive chronotropic responses of right atria of guinea-pigs to isoprenaline and forskolin were examined. An increase in sensitivity of the three preparations to isoprenaline was observed by lowering the bath temperature from 38 to 30 degrees C as demonstrated by a leftwards shift of the concentration-response curves. A similar degree of supersensitivity was observed for forskolin. Since forskolin is reputed to stimulate adenylate cyclase directly, whereas isoprenaline stimulates via the regulatory nucleotide Ns protein, this would suggest a common site for the supersensitivity at adenylate cyclase. However, the possibility that forskolin also stimulates via the Ns protein in producing cardiac stimulation and that this is the site of hypothermia-induced supersensitivity is discussed. Supersensitivity to isoprenaline was also observed in left atria and papillary muscles from guinea-pigs chronically pretreated with reserpine for 3 days (5 mg/kg at 72 h, 3 mg/kg at 48 and 24 h) or 7 days (0.1 mg/kg daily). In the same tissues, there was no change in the sensitivity to forskolin. The site of the supersensitivity can therefore be concluded to occur before the level of adenylate cyclase activation either directly or via the regulatory Ns protein possibly at the beta-adrenoreceptor itself.
Publisher: Wiley
Date: 22-06-2009
DOI: 10.1111/J.1474-8673.2009.00437.X
Abstract: 1 The internal anal sphincter (IAS) has a spontaneous tone and is the main contributor to the maintenance of faecal continence. The spontaneous resting tone exhibited by the sphincter can be modified by neurotransmitters from the autonomic and enteric nervous systems. 2 In this review, the influence of the sympathetic and parasympathetic nervous systems on IAS tone are discussed and the putative roles of nitric oxide, carbon monoxide, vasoactive intestinal peptide and adenosine triphosphate in non-adrenergic non-cholinergic transmission are considered. 3 Faecal incontinence is a common condition that places a heavy financial burden on the health service and severely affects patients' quality of life. Resting anal pressure is reduced in patients with faecal incontinence and agents that increase sphincter tone tend to relieve symptoms. The results of clinical studies of the use of phenylephrine to treat faecal incontinence are reviewed. 4 It is concluded that the IAS is a potential target for drug development for the treatment of faecal incontinence.
Publisher: Elsevier BV
Date: 1985
DOI: 10.1016/0014-2999(85)90279-1
Abstract: The inotropic and chronotropic responses of guinea pig atria, and the relaxation responses of guinea pig intestine, trachea, lung, uterus and vas deferens to catecholamines have been examined at bath temperatures of 38 degrees C and 30 degrees C. Hypothermia resulted in a supersensitivity of cardiac tissues with a decrease in isoprenaline EC50 and an increase in the maximum response to the partial agonist, salbutamol. Ileum responses to isoprenaline were potentiated at 30 degrees C but no partial agonist could be found on this tissue. Responses of the lung and vas deferens to partial agonists were not affected by temperature, while uterine responses were inhibited by hypothermia. The trachea was supersensitive to isoprenaline at 30 degrees C, however this was not due to a change in beta-adrenoceptor sensitivity but an inhibition of COMT. Partial agonist responses of trachea were similar at both temperatures. beta-Adrenoceptor supersensitivity was therefore observed only where responses are mediated primarily by beta 1-adrenoceptors and supports the concept that beta 1- but not beta 2-adrenoceptors exhibit hypothermia-induced supersensitivity.
Publisher: Springer Science and Business Media LLC
Date: 23-10-2023
Publisher: Springer Science and Business Media LLC
Date: 04-1985
DOI: 10.1007/BF00501207
Abstract: Glucocorticoids have important effects on renal function, including the modulation of renal acidification by the major proximal tubular Na(+)/H(+) exchanger, NHE3. While the chronic effect of glucocorticoids is considered to be primarily at the transcriptional level, with increases in NHE3 mRNA and protein expression driving increased transport activity, the mechanisms by which glucocorticoids activate NHE3 in an acute setting have not been investigated. Previous studies have shown that a glucocorticoid-stimulated increase in NHE3 activity can occur before any detectable change in NHE3 mRNA. The present study examines the acute effects of glucocorticoids on NHE3 using opossum kidney (OKP) cells as a cell model. In OKP cells, total NHE3 protein abundance was not changed by 3 h of treatment with dexamethasone (10(-6) M). However, the biotin-accessible fraction representing NHE3 at the apical membrane as well as Na(+)/H(+) exchange activity measured fluorimetrically using the pH-sensitive dye BCECF-AM were significantly increased. These effects were not prevented by the protein synthesis inhibitor cycloheximide. NHE3 insertion (biotinylatable NHE3 after sulfo-NHS-acetate blockade) was stimulated by dexamethasone incubation, with or without cycloheximide. The rate of NHE3 endocytic retrieval, assessed either by the avidin protection assay (early endocytosis) or by the sodium 2-mercaptoethane sulfonate (MesNa) cleavage assay (early and late endocytosis), was not affected by dexamethasone. These findings suggest that trafficking plays a key role in the acute stimulation of NHE3 by glucocorticoids, with exocytosis being the major contributor to the glucocorticoid-induced rapid increase in cell surface NHE3 protein abundance and Na(+)/H(+) exchange activity.
Publisher: Walter de Gruyter GmbH
Date: 27-03-2009
DOI: 10.2478/S11536-008-0082-2
Abstract: The aim of the study was to determine pathways involved in contraction and relaxation of the mouse urinary bladder. Mouse bladder strips were set up in gassed Krebs-bicarbonate solution and responses to various drugs and electrical field stimulation were obtained. Isoprenaline (b-receptor agonist) caused a 63% inhibition of carbachol precontracted detrusor (EC50=2nM). Carbachol caused contraction (EC50=0.3µM), responses were antagonised more potently by 4-DAMP (M3-antagonist) than methoctramine (M2-antagonist). Electrical field stimulation caused contraction, which was inhibited by atropine (60%) and less by guanethidine and α,β-methylene-ATP. The neurogenic responses were not potentiated by inhibition of nitric oxide synthase. Presence of an intact urothelium significantly depressed responses to carbachol (p=0.02) and addition of indomethacin and L-NNA to remove prostaglandin and nitric oxide production respectively did not prevent the inhibitory effect of the urothelium. In conclusion, b-receptor agonists cause relaxation and muscarinic agonists cause contraction via the M3-receptor. Acetylcholine is the main neurotransmitter causing contraction while nitric oxide has a minor role. The mouse and human urothelium are similar in releasing a factor that inhibits contraction of the detrusor muscle which is unidentified but is not nitric oxide or a prostaglandin. Therefore, the mouse may be used as a model to study the lower urinary tract.
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.UROLOGY.2012.09.011
Abstract: To investigate the role of adrenoceptor subtypes in regulating the spontaneous contractile activity of the inner lining of the urinary bladder (urothelium/lamina propria). The responses of isolated strips of porcine urothelium/lamina propria to noradrenaline, phenylephrine, and isoprenaline were obtained in the absence and presence of receptor subtype-selective antagonists. Quantitative reverse-transcriptase polymerase chain reaction was undertaken to assess the expression of adrenoceptor genes. The tissues expressed all α1- and β-adrenoceptor subtypes, with the α1A-, α1B-, and β2-adrenoceptors the predominant receptors at the messenger RNA level. In the functional experiments, the rate of phasic contractions and the basal tension were increased by the α1-adrenoceptor agonists phenylephrine (100 μM) and A61603 (10 μM). The rate and tension responses to phenylephrine were reduced by low concentrations of tamsulosin (3 nM) and RS100329 (10 nM) but were unaffected by BMY7378 (100 nM), prazosin (10 nM), and RS17053 (1 μM). In contrast, isoprenaline and salbutamol (both 1 μM) induced a relaxation of tissues and slowing of phasic contractions. The rate and tension responses to isoprenaline were inhibited by propranolol (100 nM) or a combination of CGP20712A (30 nM) and ICI118551 (70 nM). The rate responses were also significantly inhibited by ICI118551 alone (70 nM). Although all α1- and β-adrenoceptor subtypes were expressed in the pig urothelium/lamina propria, the α1A/L-adrenoceptor appeared to mediate increases in the contractile rate and tension. The β-adrenoceptor induced inhibition of spontaneous contractile activity appears to be predominately mediated by β2-adrenoceptors, with β1- and β2-adrenoceptors possibly involved in the tension responses.
Publisher: Wiley
Date: 16-02-2016
DOI: 10.1002/PROS.23167
Abstract: Some α1 -adrenoceptor antagonists possess anti-cancer actions that are independent of α1 -adrenoceptors and the aim of these studies was to assess the relative cytotoxic potencies of α1 -adrenoceptor antagonists and the mechanisms involved in these actions. PC-3 and LNCap human prostate cancer cells were exposed to α1 -adrenoceptor antagonists (0.01-100 μM) and cell survival assessed after 24-72 hr. The levels of apoptosis, autophagy and stress related proteins were also determined. The relative cytotoxic potency order was prazosin = doxazosin > terazosin = silodosin = alfuzosin > tamsulosin on both cell types, but LNCaP cells were significantly more sensitive to these effects than PC-3 cells. Prazosin and doxazosin increased levels of apoptotsis and autophagy in both cell lines, and activated EphA2 receptors in PC-3 cells. Autophagy contributed to survival of LNCaP, but promoted cell death in PC-3 cells. Treatment with prazosin (30 μM) altered the expression of several cell stress-related proteins: elevating phospho-p38α and reducing S6 kinase in both cell lines. Surprisingly some proteins were differentially affected in the two prostate cancer cell lines: Akt and p27 increasing and HIF-1α decreasing in LNCap cells but not PC-3, while ADAMTS1 was increased in PC-3 cells only. Prazosin and doxazosin demonstrated cytotoxic actions on both castration-resistant PC-3 and androgen-sensitive LNCap prostate cancer cells. The mechanisms involved included changes in a number of proliferation and apoptosis regulatory proteins. The role of autophagy depended on the cell type, but contributed to cell death in PC3 cells.
Publisher: Wiley
Date: 02-1994
DOI: 10.1111/J.1474-8673.1994.TB00587.X
Abstract: 1. The effects of depressed sympathetic function on the inotropic responses of the heart to sympathomimetic amines have been examined in rats immunized against nerve growth factor (NGF) 6 weeks prior to the isolation of cardiac tissues. 2. The activity of tyrosine hydroxylase in cervical sympathetic ganglia and the levels of noradrenaline in ventricular tissue were significantly reduced in NGF-immunized rats. 3. Left atria and papillary muscles from NGF-immunized rats were supersensitive to the beta-adrenoceptor agonist isoprenaline when compared with controls. 4. The responses of cardiac tissues to the alpha-adrenoceptor agonist phenylephrine were unaffected by immunization. 5. These results support the hypothesis that cardiac beta- but not alpha-adrenoceptor sensitivity is regulated by the sympathetic nervous system.
Publisher: Wiley
Date: 06-1995
DOI: 10.1111/J.1474-8673.1995.TB00301.X
Abstract: 1. Studies of cardiac and vascular responses have previously demonstrated that diabetes influences the sensitivity of these tissues to adrenoceptor stimulation. Adrenoceptors are also present on platelets where they modulate aggregatory responses. The present study investigates the influence of diabetes on these platelet adrenoceptor-mediated responses. 2. Rats were made diabetic with streptozotocin and platelet aggregatory responses to ADP were examined 2 or 12 weeks later. Aggregation to ADP of platelets from 2-week-diabetic rats was similar to that of platelets from age-matched controls, but platelets from 12-week-diabetic animals exhibited an enhanced aggregation to ADP. 3. In all groups studied, beta-adrenoceptor stimulation with isoprenaline caused a concentration-dependent inhibition of aggregation to ADP, whilst alpha-adrenoceptor stimulation with adrenaline was found to potentiate aggregation to ADP. The degree of inhibition or potentiation was found to remain unchanged by diabetes of either 2 or 12 weeks duration. 4. Previously reported increases in cardiac beta-adrenoceptor sensitivity and aortic alpha-adrenoceptor sensitivity were confirmed 2-week-diabetic animals, but these sensitivity changes were not observed in 12-week-diabetic rats. 5. The results indicate that, unlike the heart and vasculature, the influences of adrenoceptor stimulation on platelet aggregation are not altered by diabetes, even when aggregation to ADP is enhanced.
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.MAD.2018.03.004
Abstract: This study investigated the role of calcium sensitisation in the regulation of ureteral contractility with ageing. Isolated ureteral strips from young (6-month old) and older (3-year old) pigs were mounted in Krebs bicarbonate solution and contractility induced by the α1-adrenoceptor agonist phenylephrine (30 and 300 μM) and 5-HT (10 and 100 μM), recorded in the absence and presence of the rho-kinase inhibitors Y-27632 (10 μM) and fasudil (30 μM). Ureteral strips developed bursts of contractile activity which was measured as area under the curve (AUC) and frequency. Maximum contraction to phenylephrine was significantly enhanced in tissues from older animals compared to younger animals (p < 0.001) while maximum contraction to 5-HT was greater in tissues from younger animals (p < 0.001). Both inhibitors significantly depressed AUC and frequency responses to both agonists in ureters from both age groups (p < 0.05). Inhibition by Y-27632 of phenylephrine (300 μM)- and 5-HT(100 μM)-induced contractions was greater in tissues from older animals than young (p < 0.05). Rho-kinase activity was also assayed in ureteral tissues, and basal activity was similar in ureters from both age groups. Neither phenylephrine nor 5-HT increased rho-kinase activity over basal levels. These data demonstrate the significant role rho-kinase plays in ureteral contractility and possible alterations with age.
Publisher: Springer Science and Business Media LLC
Date: 27-04-2015
DOI: 10.1038/NCOMMS7970
Abstract: Defining the immune mechanisms underlying protective immunity to helminth infection remains an important challenge. Here we report that lung CD4(+) T cells and Group 2 innate lymphoid cells (ILC2s) work in concert to block Nippostrongylus brasiliensis (Nb) development in the parenchyma within 48 h in mice. Immune-damaged larvae have a striking morphological defect that is dependent on the expansion of IL-13-producing ILC2 and CD4(+) T cells, and the activation of M2 macrophages. This T-cell requirement can be bypassed by administration of IL-2 or IL-33, resulting in expansion of IL-13-producing ILC2s and larval killing. Depletion of ILC2s inhibits larval killing in IL-2-treated mice. Our results broaden understanding of ILC2's role in immunity to helminths by demonstrating that they not only act as alarmin sensors, but can also be sustained by CD4(+) T cells, ensuring both the prompt activation and the maintenance of IL-13-dependent M2 macrophage immunity in the lung.
Publisher: Wiley
Date: 10-02-2001
DOI: 10.1046/J.1365-2680.2001.00203.X
Abstract: 1. It has been postulated that stimulation of myocardial alpha-adrenoceptors is one of the primary mediators of the dysrhythmias which occur during periods of myocardial ischaemia and reperfusion. This study examines arrhythmogenesis during coronary artery occlusion and reperfusion in isolated perfused rat hearts from control animals and from rats with enhanced myocardial alpha-adrenoceptor responsiveness. 2. Rats were administered propylthiouracil (PTU) in their drinking water for 8 weeks. This treatment resulted in an enhanced responsiveness of isolated left atria to the alpha-adrenoceptor agonist phenylephrine compared with atria from control animals. 3. In Langendorff-perfused isolated hearts, the spontaneous rate of contraction was significantly lower in the PTU-pretreated group than in either age-matched or weight-matched controls. Occlusion of the left anterior descending artery (LAD) for 25 min resulted in ventricular tachycardia (VT) of similar incidence and duration in all groups and ventricular fibrillation (VF) in both control groups but not the PTU-pretreated group. 4. Following the 25-min ischaemic period the myocardium was reperfused for 10 min. The incidence and duration of VT and VF during this period was similar in all groups except that the duration of VF in the PTU-pretreated group was significantly lower than in controls. 5. In perfused hearts paced at 4 Hz, the incidence and duration of dysrhythmias during ischaemia and reperfusion was again similar in all groups, only the duration of VF being affected (reduced) by PTU-pretreatment. 6. In conclusion, this study does not lend support to the hypothesis that myocardial alpha-adrenoceptors have a primary role in arrhythmogenesis, but the data would support a role for these receptors in myocardial protection.
Publisher: Wiley
Date: 19-03-2015
DOI: 10.1111/AAP.12023
Abstract: Alpha1 -adrenoceptor antagonists can cause ejaculatory dysfunction as an adverse effect. Contractions of the human vas deferens are mediated via α1A -adrenoceptors, and this study investigated whether the low affinity state of this receptor (α1L -adrenoceptor) is involved in mediating contractions of this tissue. The potency of agonists and the affinity of receptor subtype selective antagonists were determined in functional experiments and in [(3) H]tamsulosin binding experiments to identify the α1 -adrenoceptor subtype population present in the human vas deferens. The α1A -adrenoceptor selective agonist A61603 was a full agonist and was 250-fold more potent than noradrenaline. Prazosin antagonized contractile responses to phenylephrine with a low affinity (pKd = 8.6). Only high concentrations of RS17053 antagonized responses to phenylephrine and yielded a relatively low affinity estimate of 7.0. BMY7378 (α1D -adrenoceptor selective) gave a low affinity estimate (pKd = 6.7), whilst tamsulosin (α1A - and α1D -adrenoceptor selective) had a high affinity (pKd = 9.9). [(3) H]Tamsulosin bound to human vas deferens membranes with a high affinity (pKd = 10.0). Prazosin, RS17053 and BMY7378 competed with [(3) H]tamsulosin with low affinities for a single population of binding sites (pKd values of 8.5, 7.2 and 6.3, respectively). These functional and radioligand binding data indicate that the human vas deferens possesses a homogeneous population of α1 -adrenoceptors which have the pharmacological properties of the putative α1L -adrenoceptor, the same functional receptor previously identified in the human prostate.
Publisher: Elsevier BV
Date: 11-2002
DOI: 10.1016/S0090-4295(02)01803-4
Abstract: Anticholinergic agents are the most widely used therapy for urge incontinence despite exerting adverse effects, such as constipation, tachycardia, and dry mouth, that limit their use. These adverse effects result from a lack of selectivity for the bladder over other organs. Although M2-muscarinic receptors are the predominant cholinoreceptor present in urinary bladder, the smaller population of M3-receptors appears to be the most functionally important and mediates direct contraction of the detrusor muscle. M2-receptors modulate detrusor contraction by several mechanisms and may contribute more to contraction of the bladder in pathologic states, such as bladder denervation or spinal cord injury. Prejunctional inhibitory M2-receptors or M4-receptors and prejunctional facilitatory M1-muscarinic receptors in the bladder have also been reported, but their relevance to the clinical effectiveness of muscarinic antagonists is unknown. In clinical studies, tolterodine, a nonselective muscarinic antagonist, has been reported to be equally effective to oxybutynin but to induce less dry mouth. Controlled-release and intravesical, intravaginal, and rectal administrations of oxybutynin have all been reported to cause fewer adverse effects. Conversely, darifenacin, a new M3-selective antagonist, has been reported to have selectivity for the bladder over the salivary gland in vivo. Whether M3-selective or nonselective muscarinic antagonists will be the most clinically effective for the overactive bladder-preserving the best balance between efficacy and tolerability-has yet to be established, and comparative clinical trials between compounds, such as darifenacin (M3 selective) and tolterodine (nonselective) will be required.
Publisher: Wiley
Date: 28-03-2023
DOI: 10.1002/NAU.25176
Abstract: Antimuscarinic medications are the first‐line treatments for overactive bladder, the most common form of bladder dysfunction. Their primary action is thought to block detrusor muscarinic receptors. It is unclear, however, if these therapeutics have actions on other tissues within the lower urinary tract. This study assessed whether clinical antimuscarinics have a functional impact on urothelium with lamina propria (U& LP) tissue. Strips of porcine detrusor and U& LP were mounted in carbogen‐gassed Krebs‐bicarbonate solution at 37°C. The tissues were paired with carbachol‐response curves performed in the absence or presence of each antimuscarinic. pEC50 values for each curve were analyzed and estimated affinities calculated. Both detrusor and U& LP tissues contracted with muscarinic receptor stimulation, which was inhibited by commonly used antimuscarinics. In detrusor s les ( p 0.001 for all), right parallel shifts from the control were observed in response to oxybutynin (1 µM), solifenacin (1 µM), tolterodine (1 µM), darifenacin (100 nM), trospium (100 nM) and fesoterodine (100 nM). This shift was consistent in U& LP s les, with no significant differences between the two layers. The data suggests that clinical antimuscarinics are as effective at inhibiting tonic contractions of the U& LP as they are on detrusor, presenting the U& LP as an alternate target of these medications in the treatment of lower urinary tract symptoms.
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.CEB.2014.05.002
Abstract: In the lymph node, T cells migrate rapidly and with striking versatility in a continuous scan for antigen presenting dendritic cells. The scanning process is greatly facilitated by the lymph node structure and composition. In vivo imaging has been instrumental in deciphering the spatiotemporal dynamics of intranodal T cell migration in both health and disease. Here we review recent developments in uncovering the migration modes employed by T cells in the lymph node, the underlying molecular mechanisms, and the scanning strategies utilised by T cells to ensure a timely response to antigenic stimuli.
Publisher: Wiley
Date: 06-1999
DOI: 10.1046/J.1464-410X.1999.00101.X
Abstract: To examine the potencies of the potassium-channel openers (KCOs) levcromakalim and YM934 as relaxing agents on human detrusor and human mesenteric artery smooth muscle, and to determine their bladder-vascular selectivity in vitro. Strips of human detrusor muscle and mesenteric artery (with the endothelium removed) were set up in physiological salt solution and the tension developed by the tissues recorded. Tissues were precontracted with a concentration of carbachol (detrusor) or phenylephrine (artery) which caused 80% of maximal contraction, and relaxation responses to levcromakalim and YM934 were then obtained. Both KCOs caused relaxation of the bladder detrusor muscle and the mesenteric artery. Maximal responses, when plotted as a percentage of the precontraction, were greater for both KCOs in the bladder muscle than the artery, but the differences were small and not statistically significant. The sensitivity (drug potency) of the detrusor muscle to the KCOs was more than twice that of the artery but this selectivity was only statistically significant for YM934. Only minor bladder-vascular selectivity for levcromakalim and YM934 could be detected in vitro. This suggests that neither drug would be tolerated clinically, although the results suggest that further development of bladder-selective KCO agents appears feasible.
Publisher: American Physiological Society
Date: 10-2018
DOI: 10.1152/AJPRENAL.00106.2018
Abstract: Tachykinins are expressed within bladder-innervating sensory afferents and have been shown to generate detrusor contraction and trigger micturition. The release of tachykinins from these sensory afferents may also activate tachykinin receptors on the urothelium or sensory afferents directly. Here, we investigated the direct and indirect influence of tachykinins on mechanosensation by recording sensory signaling from the bladder during distension, urothelial transmitter release ex vivo, and direct responses to neurokinin A (NKA) on isolated mouse urothelial cells and bladder-innervating DRG neurons. Bath application of NKA induced concentration-dependent increases in bladder-afferent firing and intravesical pressure that were attenuated by nifedipine and by the NK2 receptor antagonist GR159897 (100 nM). Intravesical NKA significantly decreased bladder compliance but had no direct effect on mechanosensitivity to bladder distension (30 µl/min). GR159897 alone enhanced bladder compliance but had no effect on mechanosensation. Intravesical NKA enhanced both the litude and frequency of bladder micromotions during distension, which induced significant transient increases in afferent firing, and were abolished by GR159897. NKA increased intracellular calcium levels in primary urothelial cells but not bladder-innervating DRG neurons. Urothelial ATP release during bladder distention was unchanged in the presence of NKA, whereas acetylcholine levels were reduced. NKA-mediated activation of urothelial cells and enhancement of bladder micromotions are novel mechanisms for NK2 receptor-mediated modulation of bladder mechanosensation. These results suggest that NKA influences bladder afferent activity indirectly via changes in detrusor contraction and urothelial mediator release. Direct actions on sensory nerves are unlikely to contribute to the effects of NKA.
Publisher: Elsevier BV
Date: 1998
DOI: 10.1159/000052277
Abstract: Receptors involved in neurotransmission are an important target for drug therapy and the identification and development of receptor-specific compounds is an essential part of contemporary drug development. Antagonists acting at detrusor muscarinic receptors and prostatic adrenergic receptors are now established therapies for the treatment of bladder instability and benign prostatic hyperplasia, respectively. Future developments await the results of basic pathophysiological studies to establish the role of classical and nonadrenergic, noncholinergic neurotransmission in the development and maintenance of diseases of the lower urinary tract. With the development of better pharmacological tools and molecular biological techniques, receptor properties are likely to be found to be tissue-specific, making the development of drugs with true tissue specificity and fewer side effects a reality.
Publisher: Wiley
Date: 2003
DOI: 10.1002/NAU.10130
Abstract: To investigate the role of beta-adrenoceptor subtypes in mediating relaxation of the pig bladder trigonal muscle in vitro. Longitudinal strips of trigonal muscle were isolated, and the mucosa and serosa removed. Tissues were precontracted with KCl, and beta-adrenoceptor agonists (isoprenaline or salbutamol) were added cumulatively, and concentration-relaxation curves (CRCs) were obtained. CRCs to agonists were obtained in the absence and presence of antagonists and antagonist affinity values were calculated. Isoprenaline (non-selective beta-agonist) relaxed with high potency (pEC(50) = 7.2). Propranolol antagonized CRCs to isoprenaline with a high affinity (apparent pK(B) = 8.8), but the Schild plot had a slope significantly (P < 0.01) less than unity (0.61), suggesting that responses were mediated by more than one beta-adrenoceptor subtype. CGP20712A (beta(1)-antagonist) antagonized responses to isoprenaline with a low affinity (apparent pK(B) = 5.13), indicating beta(1)-adrenoceptors did not participate in the response. The affinity of ICI118551 (beta(2)-antagonist) for antagonism of responses to isoprenaline was also relatively low (apparent pK(B) = 6.9), and the Schild slopes were significantly (P < 0.01) less than unity (0.58). SR59230A (beta(3)-antagonist) antagonized CRCs to isoprenaline with a relatively low affinity (apparent pK(B) = 7.5), and with a Schild slope significantly (P < 0.01) less than unity (0.86), indicating that responses may be mediated by more than one beta-adrenoceptor subtype. In contrast to that observed with isoprenaline, the beta(2)-adrenoceptor selective agonist salbutamol induced relaxation with a relatively low potency (pEC(50) = 6.6) and with maximum responses of 80% of that to isoprenaline. ICI118551 competitively antagonized (Schild plot of unity) responses to salbutamol with a high affinity (pA2 = 8.3). These data suggest that beta-adrenoceptor mediated responses to isoprenaline of the bladder trigone are mediated via both the beta(2)- and beta(3)-adrenoceptor subtypes whilst responses to salbutamol appear to be mediated only via the beta(2)-adrenoceptor.
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.TAAP.2016.12.011
Abstract: Intravesical gemcitabine has recently been introduced for the treatment of superficial bladder cancer and has a favourable efficacy and toxicity profile in comparison to mitomycin c (MMC), the most commonly used chemotherapeutic agent. The aim of this study was to assess the cytotoxic potency of gemcitabine in comparison to MMC in urothelial cell lines derived from non-malignant (UROtsa) and malignant (RT4 and T24) tissues to assess selectivity. Cells were treated with gemcitabine or mitomycin C at concentrations up to the clinical doses for 1 or 2h respectively (clinical duration). Treatment combined with hyperthermia was also examined. Cell viability, ROS formation, urothelial function (ATP, acetylcholine and PGE2 release) and secretion of inflammatory cytokines were assessed. Gemcitabine displayed a high cytotoxic selectivity for the two malignant cell lines (RT4, T24) compared to the non-malignant urothelial cells (UROtsa, proliferative and non-proliferative). In contrast, the cytotoxic effects of MMC were non-selective with equivalent potency in each of the cell lines. The cytotoxic effect of gemcitabine in the malignant cell lines was associated with an elevation in free radical formation and was significantly decreased in the presence of an equilibrative nucleoside transporter inhibitor. Transient changes in urothelial ATP and PGE
Publisher: Elsevier BV
Date: 07-2010
Publisher: Wiley
Date: 12-02-2018
DOI: 10.1111/IMR.12631
Abstract: Mast cells are a part of the innate immune system implicated in allergic reactions and the regulation of host-pathogen interactions. The distribution, morphology and biochemical composition of mast cells has been studied in detail in vitro and on tissue sections both at the light microscopic and ultrastructural level. More recently, the development of fluorescent reporter strains and intravital imaging modalities has enabled first glimpses of the real-time behavior of mast cells in situ. In this review, we describe commonly used imaging approaches to study mast cells in cell culture as well as within normal and diseased tissues. We further describe the interrogation of mast cell function via imaging by providing a detailed description of mast cell-nerve plexus interactions in the intestinal tract. Together, visualizing mast cells has expanded our view of these cells in health and disease.
Publisher: Wiley
Date: 09-1995
DOI: 10.1111/J.1476-5381.1995.TB16380.X
Abstract: 1. The predominant alpha 1-adrenoceptor mediating contractions of the human vas deferens has been characterised in vitro by use of subtype selective antagonists. 2. Responses of human epididymal vas deferens were obtained to phenylephrine in the presence of amine uptake inhibitors and propranolol. The effects of the alpha 1-adrenoceptor antagonists, 5-methylurapidil, oxymetazoline, WB4101, prazosin and chloroethylclonidine were examined and also the L-type calcium channel blocker, nifedipine. 3. 5-Methylurapidil, WB4101, oxymetazoline and prazosin acted as competitive antagonists of the responses to phenylephrine, yielding pA2 values of 8.8, 9.2, 7.7 and 8.8 respectively. All four antagonists produced Schild plots with slopes similar to unity and maximum responses to phenylephrine were not altered in the presence of any of the antagonists. 4. Tamsulosin (1 nM) caused rightward shifts of phenylephrine concentration-response curves yielding an apparent pKB value of 10.0. However, maximum responses were also reduced by 51% with this concentration of antagonist. 5. Incubation of tissues with chloroethylclonidine (100 microM for 40 min) failed to alter responses significantly but the presence of nifedipine (1 microM) reduced maximum responses to phenylephrine by 32%. 6. The high affinity of 5-methylurapidil, oxymetazoline and WB4101, together with the failure of chloroethylclonidine to antagonize responses, indicate that the predominant alpha 1-adrenoceptor mediating contraction of the human vas deferens has the characteristics previously described for the pharmacologically-defined alpha 1A-adrenoceptor. The data are also consistent with those described for the cloned alpha 1c-adrenoceptor subtype thereby supporting the hypothesis that the two receptors are identical. The human vas deferens therefore represents a readily accessible preparation for functional studies of the human alpha 1A-adrenoceptor.
Publisher: Oxford University Press (OUP)
Date: 08-1995
DOI: 10.1111/J.2042-7158.1995.TB05854.X
Abstract: The effect of 17β-oestradiol pretreatment and the natural oestrous cycle on responses of rat cardiac and vascular α-adrenoceptors was investigated. It was found that treatment with the oestrogen had no effect on cardiac adrenoceptor sensitivity, while pretreatment with the hormone caused a significant increase in vascular α2-, but not vascular α1-adrenoceptor responsiveness. Pressor responses of pithed rats to selective oer or α2-adrenoceptor agonists did not alter, however, during the natural oestrous cycle. These findings suggest that changes in oestrogen levels are capable of altering α-adrenoceptor-mediated vascular responses but that the relatively small changes in oestrogen which may occur throughout the natural oestrous cycle do not appear to alter the responses of these vascular α-adrenoceptors.
Publisher: Informa UK Limited
Date: 04-2012
DOI: 10.4161/AUTO.19496
Publisher: Informa UK Limited
Date: 1999
DOI: 10.1080/003655299750026452
Abstract: This study sought to determine whether there is a positive correlation between gallbladder emptying, biliary pain, and in vitro contractility. Ultrasound measurements were carried out on 25 gallstone patients. The response of gallbladder strips to 1.75*10(-11) to 5.25*10(-7) M cholecystokinin-8 was recorded. In a second study 23 patients filled in pain questionnaires, and in vitro studies were again carried out. Of five patients with no gallbladder emptying, four had in vitro contraction. Overall, a significant, positive linear correlation was found (P < 0.0001). In the second study in vitro contractility showed a positive linear correlation with pain. Gallbladder emptying correlates with contractility. However, since most 'non-contractors' can contract, we suggest the term 'non-emptying' or 'emptying' to describe gallbladder dynamics. The positive correlation between pain and contractility suggests that biliary pain has a muscular component.
Publisher: Wiley
Date: 09-10-2008
Publisher: Springer Science and Business Media LLC
Date: 03-02-2015
DOI: 10.1007/S00210-015-1092-7
Abstract: Intravesical mitomycin C (MMC) is commonly used to treat bladder cancer but is associated with local adverse effects. Here, we investigate the effects of MMC on release of urothelial mediators and production of inflammatory cytokines. Recovery and the effects of repeat treatment were also investigated. Urothelial cells were treated with MMC for 2 h at 37 °C. Immediately, 24 h and 7 days following MMC treatment, effects were assessed in terms of changes in ATP, acetylcholine and PGE2 release, and the presence of inflammatory cytokines and nitric oxide in incubation medium. Endpoints were also assessed 7 days after repeat MMC treatment. Immediately following MMC treatment at the clinical concentration (2 mg/mL), stretch-induced ATP release was significantly decreased, basal acetylcholine release was enhanced, while basal PGE2 was depressed and response to stretch increased. Twenty-four hours after treatment, basal acetylcholine was significantly increased ([MMC] ≥0.0002 mg/mL) and basal PGE2 enhanced (0.02 mg/mL). A 326-fold increase in interleukin-8 secretion and significant increase in nitric oxide release were also detected at 24 h. One week after single and repeat MMC treatment, urothelial ATP, acetylcholine and PGE2 had recovered while the increase in nitric oxide and interleukin-8 was still evident. These results indicate that urothelial mediator release is affected by MMC treatment with full recovery by 1 week. However, a concurrent increase in secretion of the inflammatory cytokine interleukin-8 and nitric oxide was also detected 24 h following treatment, which were still evident after the recovery period. These changes may play a role in the local adverse effects associated with intravesical MMC treatment.
Publisher: Wiley
Date: 10-08-2017
Abstract: The urethral uroepithelium has been implicated in urethral sensation and maintenance of continence. However, relatively little is known about the function of the urethral urothelium compared with that of the bladder. The aim of the study was to examine the role of the urothelium/lamina propria on contractility of the porcine urethra, along with the influence of nitric oxide, prostaglandins and ageing. Porcine urethral tissues, intact and denuded of urothelium/lamina propria, were mounted in tissue baths and contractions to noradrenaline, phenylephrine and carbachol obtained. Contractions in the presence of Nώ-nitro-l-arginine (100 μmol/L) and indomethacin (10 μmol/L) were examined, along with contractions of tissues from young (6 months) and older (3 years) animals. The urothelium/lamina propria of the urethra significantly inhibited contractions to carbachol, noradrenaline and phenylephrine. This inhibitory effect was not significantly different for the three agonists (58.7±10.3%, 60.4±12.6% and 39.4±12.2% inhibition n=4-7), and was also observed when denuded tissues were co-incubated with a second tissue with intact urothelium/lamina propria (40.6±7.5% inhibition n=6). Inhibition of nitric oxide and prostaglandin production did not attenuate the inhibitory effect of the urothelium/lamina propria on noradrenaline contractions. In addition, ageing did not alter the inhibitory effect for either phenylephrine contractions (33.9±2.2% vs 41.0±9.7%, young vs older urethral tissues) or noradrenaline contractions (32.9±11.1% vs 53.7±11.0%). In conclusion the urothelium/lamina propria of the urethra has an inhibitory effect on receptor-mediated urethral contraction. This inhibition is due to the release of a diffusible factor, and the effect is not mediated by nitric oxide or prostaglandins, or affected by age.
Publisher: Hindawi Limited
Date: 2014
DOI: 10.1155/2014/204604
Abstract: ATP is an important mediator of urgency in women with detrusor overactivity (DO). In order to understand how different degrees of bladder stretch elicited ATP release in DO patients compared with controls, sequential aliquots were collected during cystometry and ATP release was measured at each degree of bladder filling, in female patients with DO and controls. In both DO and control groups, ATP release was induced during bladder filling, suggesting that stretch stimulated further ATP release. However, the luminal ATP concentrations were already high at early filling stage (200 mL), which was even greater than those at the later filling stages (400 mL and maximum cystometric capacity, MCC), indicating that a substantial ATP release has been induced during early filling (200 mL) in both DO and controls. In DO, ATP release at 200 mL was significantly higher in those with low first desire to void (FDV) (≤200 mL) than in those with higher FDV ( mL) this may suggest that ATP release at early stretch may play an important role in urgency (early sensation) in DO. ATP concentrations remained unchanged after voiding, suggesting that voiding did not further induce ATP release into intraluminal fluid.
Publisher: Wiley
Date: 28-04-2009
DOI: 10.1111/J.1348-0421.2009.00125.X
Abstract: Due to multiple-drug resistant bacteria, phage therapy is being revisited. Although most animal experiments focus on therapeutic efficacy, the blood clearance kinetics of phages have not been well described. For further development of an efficient therapeutic strategy, information on phage blood kinetics is important. In this study, time-course concentration changes in peripheral blood of healthy and neutropenic mice were measured using four therapeutic phages (phiMR11, KPP10, phiEF24C, and KEP10). The results showed a two- to three-day rapid phage clearance, which fits a two-compartment model.
Publisher: Springer Science and Business Media LLC
Date: 11-02-2017
DOI: 10.1007/S00210-017-1355-6
Abstract: In men, testosterone levels decline by 1% per year after the age of 40. Reduced androgen levels may directly contribute to lower urinary tract symptoms and bladder dysfunction, although the mechanisms are unclear. This study examined the effect of low testosterone and testosterone replacement on key mechanisms involved in local bladder function. Intraluminal release of the mediators ATP and ACh in response to bladder distension was measured in whole bladders from rats 8 weeks following castration, whilst bladder contractility was assessed using isolated strips. Human urothelial cells were cultured under low, physiological and supra-physiological testosterone conditions for 24 h or 5 days, and stretch-induced release of ATP and ACh was measured. Phasic contractile activity of bladder strips, agonist-induced reponses to carbachol and isoprenaline and nerve-evoked contractions were unaffected by castration. The acetylcholinesterase inhibitor neostigmine significantly increased litude of phasic activity only in bladder strips following castration, and this was prevented by testosterone replacement. Intraluminal ACh release following bladder distension was significantly reduced following castration, whilst ATP release was unaffected. In contrast, stretch-induced ATP release from urothelial cells was significantly enhanced in low testosterone conditions, whilst ACh release was unaltered. Testosterone-replacement to physiological levels prevented these changes. Whilst androgen deficiency of 8 weeks does not directly affect contractility of bladder smooth muscle, urothelial mediator release is sensitive to changes in testosterone. These changes in mediator release may be an early effect of the decline in testosterone and could affect sensory pathways in the longer term, contributing to the urinary symptoms and bladder dysfunction seen in androgen-deficient men.
Publisher: Elsevier BV
Date: 06-2010
DOI: 10.1016/J.EURURO.2009.11.042
Abstract: There is increased evidence to suggest a role for nonadrenergic-noncholinergic neurotransmission in the pathogenesis of bladder dysfunction. In this set of experiments, we have assessed the contribution of the urothelium to purinergic activity by quantifying the amount of adenosine triphosphate (ATP) released from the urothelium of patients with idiopathic detrusor overactivity (IDO) and with neurogenic detrusor overactivity (NDO) and comparing these releases to those of controls. Bladder tissue with urodynamically and clinically proven NDO (n=8) and IDO (n=8) were included in this study. The carefully dissected urothelium was stimulated by mechanically stretching as well as electrically stimulating and the ATP thus, release was quantified. We used a Lucy Anthos 1 luminometre (Anthos Labtec Instruments GmBH, Wals, Austria) to perform the assay. The results were analysed using Stingray software (Dazdaq Ltd, Brighton, UK). Both mechanical stretch and electric field stimulation (EFS) led to increased ATP release in both sets of tissues with overactivity compared to the controls this rise was even more significant for the IDO urothelium (2416.7±479.8 pmol/g [p<0.005]) than for the NDO urothelium (133.1±22.4 pmol/g [p<0.01]) values for the controls were 77.6±16.2 pmol/g. ATP release following mechanical stretch was more sensitive to tetrodotoxin in bladders with NDO compared to those with IDO as well as to the controls, with ATP levels falling from 233.5±20.7 pmol/g to 107.2±11.6 pmol/g, expressed as percentage of basal levels (p<0.002). The experiments were performed in vitro, and the female patients were a mix of peri- and postmenopausal states. These experiments suggested a significant rise in ATP release from the urothelium of bladders with NDO as well as those with IDO in comparison to controls. Most of the ATP released from bladders with NDO is primarily from neuronal sources.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: Australia
No related grants have been discovered for Russ Chess-Williams.