Muscle fatigue in frog semitendinosus: alterations in contractile function.
Muscle fatigue in frog semitendinosus: alterations in contractile function.
复制标题
青蛙半腱肌疲劳：收缩功能的改变。
DOI：
10.1152/ajpcell.1992.262.6.c1500
复制
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：
--
作者：
Thompson,LV;Balog,EM;Riley,DA;Fitts,RH
本研究的目的是表征青蛙半腱肌 (ST) 在疲劳恢复之前和恢复过程中的收缩特性，将观察到的功能变化与肌肉收缩的横桥模型中特定步骤的变化联系起来，并确定疲劳如何影响力-频率关系。青蛙 ST（22 摄氏度）因 1/s 的 100 毫秒 150 赫兹序列直接电刺激 5 分钟而疲劳。疲劳方案将峰值抽搐 (Pt) 和强直 (Po) 力分别降低至初始力的 32% 和 8.5%。 Pt 的下降幅度小于 Po，部分原因是等长收缩时间 (CT) 延长，增加至初始值的 300%。 CT 延长和二分之一松弛时间 (1/2RT) 增加 800% 反映了等长抽搐持续时间大大延长。 Pt 和 Po 均显示出双相恢复，快速初始阶段（2 分钟），随后较慢（40 分钟）恢复到预疲劳力。 CT和1/2RT也分两个阶段恢复，在前5分钟内恢复到160%和265%的控制。 CT 在 35 至 40 分钟之间恢复到疲劳前值，而即使在 60 分钟，1/2RT 也是对照的 133%。通过松弛测试确定的最大缩短速度在疲劳时显着降低[从 6.7 +/- 0.5 到 2.5 +/- 0.4 最佳肌肉长度/秒]。力-频率关系向左移动，从而降低了生成Po的最佳频率。（摘要截断为250字）
The purpose of this study was to characterize the contractile properties of the frog semitendinosus (ST) muscle before and during recovery from fatigue, to relate the observed functional changes to alterations in specific steps in the crossbridge model of muscle contraction, and to determine how fatigue affects the force-frequency relationship. The frog ST (22 degrees C) was fatigued by direct electrical stimulation with 100-ms 150-Hz trains at 1/s for 5 min. The fatigue protocol reduced peak twitch (Pt) and tetanic (Po) force to 32 and 8.5% of initial force, respectively. The decline in Pt was less than Po, in part due to a prolongation in the isometric contraction time (CT), which increased to 300% of the initial value. The isometric twitch duration was greatly prolonged as reflected by the lengthened CT and the 800% increase in the one-half relaxation time (1/2RT). Both Pt and Po showed a biphasic recovery, a rapid initial phase (2 min) followed by a slower (40 min) return to the prefatigue force. CT and 1/2RT also recovered in two phases, returning to 160 and 265% of control in the first 5 min. CT returned to the prefatigue value between 35 and 40 min, whereas even at 60 min 1/2RT was 133% of control. The maximal velocity of shortening, determined by the slack test, was significantly reduced [from 6.7 +/- 0.5 to 2.5 +/- 0.4 optimal muscle length/s] at fatigue. The force-frequency relationship was shifted to the left, so that optimal frequency for generating Po was reduced.(ABSTRACT TRUNCATED AT 250 WORDS)