Gossen E R, Allingham K, Sale D G
Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
Can J Physiol Pharmacol. 2001 Jan;79(1):49-58.
The effect of temperature on post-tetanic potentiation (PTP) has been examined in the muscles of small mammals but not in human skeletal muscle. We examined PTP in the ankle dorsiflexor muscles of 10 young men by evoking twitches before and after a 7-second tetanus at 100 Hz in a control (room air approximately 21 degrees C) condition and after immersion of the lower leg in warm (45 degrees C) and cold (10 degrees C) water baths for 30 min. Exposure to cold decreased tetanus and pre-tetanus twitch peak torque, but increased rise time, half-relaxation time, and muscle action potential (M-wave) amplitude; exposure to warm water had little effect. PTP was smallest in cold exposure 5 s post-tetanus, but persisted throughout the 12 min test period, whereas PTP had subsided by 6 min post-tetanus in control and warm exposures. M-wave amplitude initially decreased after exposure to warm water, recovered, then decreased again by 11 min post-tetanus. In contrast, exposure to cold had no initial effect but did increase the M-wave amplitude during the last half of the 12 min test period, similar to that seen in the control. The greatest immediate decrease in rise time and half-relaxation time was observed in the control; however, by 12 min post-tetanus warm exposure showed the greatest increase in rise time and half-relaxation time above pre-tetanus values. The decrease in the unpotentiated twitch torque with cooling in human dorsiflexors is typical for muscles with a predominance of type I (slow) fibres. The effect of cold on PTP is similar to that seen previously in mammalian muscles with a predominance of type II (fast) fibres, although the underlying mechanism of the cooling effect appears to differ.
温度对强直后增强（PTP）的影响已在小型哺乳动物的肌肉中进行了研究，但尚未在人类骨骼肌中进行。我们通过在对照（室温约21摄氏度）条件下以及在将小腿浸入温（45摄氏度）水和冷（10摄氏度）水浴30分钟后，在100Hz下进行7秒强直刺激前后诱发抽搐，来检测10名年轻男性踝背屈肌中的PTP。暴露于寒冷会降低强直刺激和强直前抽搐的峰值扭矩，但会增加上升时间、半松弛时间和肌肉动作电位（M波）幅度；暴露于温水的影响很小。强直后5秒时，寒冷暴露下的PTP最小，但在整个12分钟的测试期内持续存在，而在对照和温暖暴露中，强直后6分钟时PTP就已消退。暴露于温水后，M波幅度最初下降，随后恢复，然后在强直后11分钟再次下降。相比之下，暴露于寒冷最初没有影响，但在12分钟测试期的后半段确实增加了M波幅度，与对照中观察到的情况类似。对照中观察到上升时间和半松弛时间的最大即时下降；然而，在强直后12分钟时，温暖暴露显示上升时间和半松弛时间相对于强直前值的增加最大。人类背屈肌冷却时未增强抽搐扭矩的降低是I型（慢）纤维占优势的肌肉的典型特征。寒冷对PTP的影响与先前在II型（快）纤维占优势的哺乳动物肌肉中观察到的相似，尽管冷却效应的潜在机制似乎有所不同。
