Pagala M K, Namba T, Grob D
Muscle Nerve. 1984 Jul-Aug;7(6):454-64. doi: 10.1002/mus.880070607.
In previous studies of muscle fatigue, tension was monitored from whole muscle, while action potentials were recorded from a few muscle fibers. To compare more accurately changes in these responses, an in vitro fluid electrode technique was employed to record the action potential of whole muscle simultaneously with tension during fatigue induced by nerve stimulation in the rat extensor digitorum longus (EDL), soleus, and diaphragm muscles. In each muscle, tension declined from the start of stimulation, while action potential amplitude initially increased slightly and then declined most rapidly in EDL, more slowly in diaphragm, and most slowly in soleus. Direct stimulation of the fatigued muscle produced the greatest increase in tension in EDL, next in diaphragm, and least in soleus. These results indicate that while failure of excitation-contraction coupling or of the contractile mechanism is the initial cause of fatigue in all the muscles studied, and remains the predominant cause throughout in the soleus muscle, failure of neuromuscular transmission plays an important role in fatigue after the first 15 seconds in EDL, and to a lesser extent, after the first 90 seconds in diaphragm.
在以往关于肌肉疲劳的研究中，是从整块肌肉监测张力，而动作电位是从少数肌纤维记录的。为了更准确地比较这些反应的变化，采用了一种体外流体电极技术，在大鼠趾长伸肌（EDL）、比目鱼肌和膈肌由神经刺激诱发疲劳期间，同时记录整块肌肉的动作电位和张力。在每块肌肉中，从刺激开始张力就下降，而动作电位幅度最初略有增加，然后在EDL中下降最快，在膈肌中下降较慢，在比目鱼肌中下降最慢。直接刺激疲劳肌肉时，EDL中张力增加最大，其次是膈肌，比目鱼肌中增加最小。这些结果表明，虽然兴奋-收缩偶联或收缩机制的失效是所有研究肌肉疲劳的初始原因，并且在比目鱼肌中始终是主要原因，但神经肌肉传递的失效在EDL中刺激开始15秒后对疲劳起重要作用，在膈肌中刺激开始90秒后起较小作用。
