Van Lunteren E, Moyer M, Torres A
Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
J Appl Physiol (1985). 1998 Aug;85(2):601-8. doi: 10.1152/jappl.1998.85.2.601.
The role of ATP-sensitive K+ channels in skeletal muscle contractile performance is controversial: blockers of these channels have been found to not alter, accelerate, or attenuate fatigue. The present study reexamined whether glibenclamide affects contractile performance during repetitive contraction. Experiments systematically assessed the effects of stimulation paradigm, temperature, and presence of hypoxia and in addition compared intertrain with intratrain fatigue. Adult rat diaphragm muscle strips were studied in vitro. At 37 degrees C and normoxia, glibenclamide did not significantly affect any measure of fatigue during continuous 5- or 100-Hz or intermittent 20-Hz stimulation but progressively prolonged relaxation time during 20-Hz stimulation. At 20 degrees C and normoxia, neither force nor relaxation rate was affected significantly by glibenclamide during 20-Hz stimulation. At 37 degrees C and hypoxia, glibenclamide did not significantly affect fatigue at 5-Hz or intertrain fatigue during 20-Hz stimulation but reduced intratrain fatigue and prolonged relaxation time during 20-Hz stimulation. These findings indicate that, although ATP-sensitive K+ channels may be activated during repetitive contraction, their activation has only a modest effect on the rate of fatigue development.
ATP敏感性钾通道在骨骼肌收缩性能中的作用存在争议：已发现这些通道的阻滞剂不会改变、加速或减轻疲劳。本研究重新审视了格列本脲在重复收缩过程中是否会影响收缩性能。实验系统地评估了刺激模式、温度和缺氧的影响，此外还比较了训练间疲劳与训练内疲劳。对成年大鼠膈肌肌条进行了体外研究。在37℃和常氧条件下，格列本脲在连续5Hz或100Hz或间歇20Hz刺激期间对任何疲劳指标均无显著影响，但在20Hz刺激期间逐渐延长了舒张时间。在20℃和常氧条件下，格列本脲在20Hz刺激期间对肌力和舒张速率均无显著影响。在37℃和缺氧条件下，格列本脲在5Hz刺激时对疲劳无显著影响，在20Hz刺激期间对训练间疲劳无显著影响，但可减轻训练内疲劳并延长20Hz刺激期间的舒张时间。这些发现表明，尽管ATP敏感性钾通道可能在重复收缩期间被激活，但其激活对疲劳发展速率的影响不大。
