热诱导去膜肌纤维收缩机理的椭园偏振法研究

Thermally Induced Contraction Mechanism of the Single Skinned Muscle Fibres by Ellipsometric Method

利用自制的磁光调制瞬态椭园偏振仪，发现通过单根青蛙去膜肌纤维的衍射光的退偏率是温度的函数，当温度在３０℃左右时，退偏率呈现极小值，肌纤维张力呈突然上升趋势，而衍射光强度则随之下降。与完整青蛙肌纤维同样效应的实验结果相比较，我们认为这是由于温度接近３０℃时肌质网释放的钙离子浓度大于扩散到肌纤维内部的ＥＧＴＡ，因而游离的钙离子促使横桥由弱耦合向强耦合过渡，退偏率下降，张力增大，光强减弱。温度进一步提高会导致横桥热振动加剧，其平均效应是使横桥向粗肌丝靠扰，促使其退偏率上升、张力减小．当温度超过３５℃时，则肌纤维的内部结构遭到破坏。

It is founded that the depolarization ratio of the diffraction light from the single frog skinned muscle fibres is the function of the temperature.When the temperature is near 30℃, the curve of the depolarization ratio runs down suddenly,then goes up.In the same time the tensions of muscle gets to the maximum value and the intensity of the diffraction light is decreased.These results are coincided with the result from the intact frog muscle fibres. The model is the compilation of two mechanisms,one is the heat motion of the Ca within the SR and the other is the heat motion of the cross─bridge.