Role of parvalbumin in relaxation of frog skeletal muscle.
Role of parvalbumin in relaxation of frog skeletal muscle.
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小清蛋白在青蛙骨骼肌松弛中的作用。
DOI：
10.1007/978-1-4615-2872-2_13
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发表时间：
1993
影响因子：
--
通讯作者：
Rall,JA
中科院分区：
文献类型：
--
作者：
Hou,TT;Johnson,JD;Rall,JA
本实验旨在验证小清蛋白（PA）促进蛙骨骼肌松弛的假说。单纤维和从R.用0°C等长强直持续时间测定PA的Ca ~（2+）和Mg ~（2+）解离速率与松弛速率变化之间的关系。松弛速率减慢作为强直持续时间的函数，速率常数为1.18 s-1。长时间强直后的弛豫率恢复表现出0.12 s-1的速率常数。Mg ~（2+）和Ca ~（2+）从纯化的PA中解离的速率常数分别为0.93 S ~（-1）和0.19 S ~（-1）。因此，弛豫速率的减慢和恢复速率可能分别由Mg ~（2+）和Ca ~（2+）从PA中解离来控制。温度对弛豫速率和Ca ~（2+）和Mg ~（2+）从纯化PA解离速率的影响也进行了研究。相对于松弛速率的最终稳定值，松弛速率随强直持续时间增加而减慢的幅度在0 ℃时大于10 ℃时。在0至10°C范围内，松弛速率的Q10随着强直持续时间的增加而增加。如果肌浆网摄取Ca ~（2+）的Q_（10）大于PA在松弛过程中螯合Ca ~（2+）的Q_（10），则可以解释这两种观察结果。当Ca 2+和Mg 2+在不同温度下从PA的解离速率与其他提出的PA功能指标进行比较时，可以得出结论，PA在0至20°C范围内促进青蛙骨骼肌的松弛。
Experiments were done to test the hypothesis that parvalbumin (PA) promotes relaxation in frog skeletal muscle. Single fibers and purified PA fromR. temporariaskeletal muscle were used to determine the relationship between Ca2+and Mg2+dissociation rates from PA and changes in relaxation rate as a function of isometric tetanus duration at 0°C. Relaxation rate slows as a function of tetanus duration with a rate constant of 1.18 s-1. Recovery of relaxation rate after a prolonged tetanus exhibits a rate constant of 0.12 s-1. Dissociation rate constants for Mg2+and Ca2+from purified PA are 0.93 S-1and 0.19 S-1, respectively. Thus rates of slowing and recovery of relaxation rate may be controlled by Mg2+and Ca2+dissociation from PA, respectively. The influence of temperature on relaxation rate and on Ca2+and Mg2+dissociation rates from purified PA also was examined. The magnitude of slowing of relaxation rate with increasing tetanus duration, relative to the final, steady value of relaxation rate, is greater at 0 than at 10°C. In the 0 to 10°C range, the Q10for relaxation rate increases with increasing tetanus duration. Both of these observations can be explained if the Q10for Ca2+uptake by the sarcoplasmic reticulum is greater than the Q10for Ca2+sequestration by PA during relaxation. When Ca2+and Mg2+dissociation rates from PA at various temperatures are compared to other proposed indicators of PA function, it is concluded that PA facilitates relaxation of frog skeletal muscle in the 0 to 20°C range.