Muscle fatigue in frog semitendinosus: role of intracellular pH.
Muscle fatigue in frog semitendinosus: role of intracellular pH.
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青蛙半腱肌疲劳：细胞内 pH 值的作用。
DOI：
10.1152/ajpcell.1992.262.6.c1507
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Fitts,RH
中科院分区：
文献类型：
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作者：
Thompson,LV;Balog,EM;Fitts,RH
本研究的目的是利用玻璃微电极来表征蛙半腱肌（ST）疲劳恢复前和恢复期间的细胞内pH （pHi）。第二个目标是评估pHi和收缩函数之间的关系。采用100 ms、150 hz、1/s、持续5 min的直接电刺激，使青蛙ST肌（22℃）疲劳。峰值强直力（Po）降至初始力的8.5%，并以双相方式恢复，40 min后恢复到静息值。静息pHi值为7.00 +/- 0.02 (n = 37)，随疲劳而下降，恢复3 min时平均pHi值为6.42。在恢复期间，pHi显著增加，并在25分钟后恢复到疲劳前的值。pHi回收率与Po慢相回收率高度相关（r = 0.98, P < 0.001）。平均静息膜电位为-78 +/- 1.0 mV (n = 42)，恢复后3分钟去极化至-67 +/- 4 mV。在恢复缓慢阶段，肌力发展的峰值速率（+dP/dt） （r = 0.99, P < 0.001）和下降速率（-dP/dt） （r = 0.94, P < 0.014）与pHi高度相关。收缩时间（CT）和半松弛时间（1/2RT）均显著增加，并呈指数级恢复。CT和1/2RT的恢复均与pHi显著相关（r = -0.93, P < 0.001； CT和1/2RT的恢复r = -0.86, P < 0.001）。（摘要删节250字）
The purpose of this study was to utilize glass microelectrodes to characterize the intracellular pH (pHi) before and during recovery from fatigue in the frog semitendinosus (ST) muscle. A second objective was to evaluate the relationship between pHi and contractile function. The frog ST muscle (22 degrees C) was fatigued by direct electrical stimulation with 100-ms 150-Hz trains at 1/s for 5 min. Peak tetanic force (Po) was reduced to 8.5% of initial force and recovered in a biphasic manner, returning to the resting value by 40 min. Resting pHi was 7.00 +/- 0.02 (n = 37) and declined with fatigue to an average value of 6.42 at 3 min of recovery. During recovery pHi significantly increased and by 25 min had returned to the prefatigue value. The pHi recovery was highly correlated to the slow phase of Po recovery (r = 0.98, P less than 0.001). The mean resting membrane potential was -78 +/- 1.0 mV (n = 42) and at 3 min of recovery was depolarized to -67 +/- 4 mV. Both the peak rate of twitch force development (+dP/dt) (r = 0.99, P less than 0.001) and decline (-dP/dt) (r = 0.94, P less than 0.014) were highly correlated to pHi during the slow phase of recovery. Contraction time (CT) and one-half relaxation time (1/2RT) increased significantly and recovered exponentially. The recovery of CT and 1/2RT were both significantly correlated to pHi (r = -0.93, P less than 0.001 and r = -0.86, P less than 0.001 for CT and 1/2RT, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)