Angiotensin AT2 Receptor: A Novel Target For Cardiovascular Modulation
Funder
National Health and Medical Research Council
Funding Amount
$692,040.00
Summary
The hormone, angiotensin II, circulates in the blood and increases blood pressure and thickens the heart and blood vessels, all of which contributes to high blood pressure (hypertension). Angiotensin II causes these excitatory effects by acting at particular target sites called AT1 receptors. Drugs called AT1 receptor antagonists are known to block these excitatory actions of angiotensin II at AT1 receptors. Consequently, these compounds lower blood pressure in humans because they block the ongo ....The hormone, angiotensin II, circulates in the blood and increases blood pressure and thickens the heart and blood vessels, all of which contributes to high blood pressure (hypertension). Angiotensin II causes these excitatory effects by acting at particular target sites called AT1 receptors. Drugs called AT1 receptor antagonists are known to block these excitatory actions of angiotensin II at AT1 receptors. Consequently, these compounds lower blood pressure in humans because they block the ongoing stimulatory action of angiotensin II. However, it is now thought that angiotensin II may also be able to act at another target site (AT2 receptor) to cause opposite effects, i.e. decrease blood pressure and inhibit growth effects. Therefore, this project will examine if direct stimulation of AT2 sites can alter blood flows measured in different body regions in hypertensive rats as part of their mechanism to lower blood pressure. In addition, the effects of continuous stimulation of the AT2 site will be examined in hypertensive rats which will be implanted with a radiotransmitter to measure blood pressure without interference, and afterwards, structural measurements of the heart and blood vessels will be made. Additionally, this project will investigate whether stimulation of the AT2 site also contributes to the blood pressure-lowering effect of drugs already mentioned (AT1 receptor antagonists). The rationale for this is that the hormone angiotensin II is still 'free' to act at the AT2 site, even with AT1 receptors being blocked, and lower blood pressure. These studies will determine if stimulation of AT2 sites contributes to the beneficial effects (i.e. decreased blood pressure and decreased cardiovascular growth) of AT1 receptor antagonists in the treatment of high blood pressure. More importantly, these findings may also identify a new therapeutic target site (AT2 receptor) for drug development in the treatment of cardiovascular disease.Read moreRead less
Pharmacological Modulation Of Microglial Responses After Transient Forebrain Ischaemia In Rats
Funder
National Health and Medical Research Council
Funding Amount
$170,906.00
Summary
A stroke is caused by an acute blockade of blood flow to a brain region and is normally caused by a clot in the artery that supplies blood to that region. Within minutes, the region of the brain that is receiving no blood flow, dies and so the functions controlled by that region cease. If this region controls key functions such as breathing then the patient dies and this occurs in about one third of patients. However, in the majority of patients, the blockage affects parts of the brain controlli ....A stroke is caused by an acute blockade of blood flow to a brain region and is normally caused by a clot in the artery that supplies blood to that region. Within minutes, the region of the brain that is receiving no blood flow, dies and so the functions controlled by that region cease. If this region controls key functions such as breathing then the patient dies and this occurs in about one third of patients. However, in the majority of patients, the blockage affects parts of the brain controlling movement of limbs or speech and so these patients suffer permanent disabilities. Not surprisingly, stroke is the most common life-threatening neurological disease and the major cause of disability in adults over 45. Apart from the profound effect stroke has on the patient and the family, the annual cost of disability to the Australian community is approx $ 1 billion. If the disability could be minimised by reducing institutionalization then the cost saving would be great. Research is being carried out to define how nerves die when they have insufficient blood supply and progress has been made in understanding the biochemical basis of this process. Such knowledge opens the way for the design of novel drugs to delay nerve death. Our laboratory has been successful in designing a novel drug, AM-36 that minimises nerve death in the forebrain of rats that have had the blood supply to the forebrain interrupted for 3 to 5 hours. A recent report has shown that a stroke in the forebrain can lead to nerve damage in the spinal cord and this could contribute to impaired walking in stroke patients. This is an unexpected finding and this project seeks to define how and when nerves in the spine die after a stroke in the forebrain. Such information should then lead to the rational design of drugs to minimise the death of nerves in the spinal cord as well as in the forebrain.Read moreRead less