ORCID Profile
0000-0002-6628-0848
Current Organisation
Hiroshima University
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Publisher: Wiley
Date: 14-09-2020
DOI: 10.1113/JP279574
Publisher: Springer Science and Business Media LLC
Date: 24-06-2019
DOI: 10.1007/S10974-019-09524-Y
Abstract: The aim of this study was to investigate the effects of an enzymatic removal of glycogen on excitation-contraction coupling in mechanically skinned fibres of rat fast-twitch muscles, with a focus on the changes in the function of Na
Publisher: American Physiological Society
Date: 09-2022
DOI: 10.1152/JAPPLPHYSIOL.00327.2022
Abstract: It remains unclear whether eccentric contraction of skeletal muscle affects titin stiffness-related contractile properties. Here, we provide evidence that an acute bout of eccentric contraction can potentiate titin-based passive force, maximum active force at long sarcomere lengths, and length-dependent activation. This potentiation may resist muscle fatigue in the muscles of the exercising body.
Publisher: American Physiological Society
Date: 12-2021
DOI: 10.1152/AJPREGU.00189.2021
Abstract: This study was conducted to examine the effects of an acute bout of vigorous isometric contractions on titin stiffness-related contractile properties in rat fast-twitch skeletal muscles. Intact gastrocnemius muscles were electrically stimulated in situ until the force was reduced to ∼50% of the initial force. Immediately after cessation of the stimulation, the superficial regions of the muscles were dissected and subjected to biochemical and skinned fiber analyses. The stimulation resulted in a decrease in the titin-based passive force. The amounts of fragmented titin were unchanged by the stimulation. Protein kinase Cα-treatment increased the passive force in stimulated fibers to resting levels. The stimulation had no effect on the maximum Ca 2+ -activated force (max Ca 2+ force) at a sarcomere length (SL) of 2.4 μm and decreased myofibrillar (my)-Ca 2+ sensitivity at 2.6-μm SL. Stretching the SL to 3.0 μm led to the augmentation of the max Ca 2+ force and my-Ca 2+ sensitivity in both rested and stimulated fibers. For the max Ca 2+ force, the extent of the increase was smaller in stimulated than in rested fibers, whereas for my-Ca 2+ sensitivity, it was higher in stimulated than in rested fibers. These results suggest that vigorous isometric contractions decrease the titin-based passive force, possibly because of a reduction in phosphorylation by protein kinase Cα, and that the decreased titin stiffness may contribute, at least in part, to muscle fatigue.
Publisher: American Physiological Society
Date: 08-2023
DOI: 10.1152/AJPREGU.00097.2022
Abstract: The effects of reduced glutathione (GSH) on skeletal muscle fatigue were investigated. GSH was depressed by buthionine sulfoximine (BSO) (100 mg/kg body wt/day) treatment for 5 days, which decreased GSH content to ∼10%. Male Wistar rats were assigned to the control ( N = 18) and BSO groups ( N = 17). Twelve hours after BSO treatment, the plantar flexor muscles were subjected to fatiguing stimulation (FS). Eight control and seven BSO rats were rested for 0.5 h (early stage of recovery), and the remaining were rested for 6 h (late stage of recovery). Forces were measured before FS and after rest, and physiological functions were estimated using mechanically skinned fibers. The force at 40 Hz decreased to a similar extent in both groups in the early stage of recovery and was restored in the control but not in the BSO group in the late stage of recovery. In the early stage of recovery, sarcoplasmic reticulum (SR) Ca 2+ release was decreased in the control greater than in the BSO group, whereas myofibrillar Ca 2+ sensitivity was increased in the control but not in the BSO group. In the late stage of recovery, SR Ca 2+ release decreased and SR Ca 2+ leakage increased in the BSO group but not in the control group. These results indicate that GSH depression alters the cellular mechanism of muscle fatigue in the early stage and delays force recovery in the late stage of recovery, due at least in part, to the prolonged Ca 2+ leakage from the SR.
No related grants have been discovered for Masanobu Wada.