Oetliker H, Schümperli R A
Experientia. 1979 Apr 15;35(4):496-8. doi: 10.1007/BF01922728.
The early large birefringence signal and mechanical activity were studied together in isolated single fibres of frog skeletal muscle with double stimulation at short stimulus intervals (2-60 msec) at room temperature and at 4--6 degrees C. In all fibres tested, extra tension and additional birefringence signal in response to the second stimulus appeared simultaneously and suddenly upon increasing the stimulus interval. The shape of the stimulus-interval versus tension-development curve makes it highly improbable that subthreshold calcium release occurs at shorter stimulus intervals; therefore, tension development reliably reflects Ca-release in these experiments. In contrast to the report by Suarez-Kurtz and Partker, birefringence signal and calcium release are shown not to be dissociated by double stimulation. This result supports the hypothesis that the early large birefringence signal is an intrinsic indicator of calcium release from the sr during EC-coupling in skeletal muscle.
在室温以及4 - 6摄氏度条件下，采用短刺激间隔（2 - 60毫秒）的双刺激，对青蛙骨骼肌的分离单纤维中早期大双折射信号和机械活性进行了联合研究。在所有测试的纤维中，随着刺激间隔增加，响应第二个刺激的额外张力和额外双折射信号会同时突然出现。刺激间隔与张力发展曲线的形状表明，在较短刺激间隔下发生阈下钙释放的可能性极小；因此，在这些实验中，张力发展可靠地反映了钙释放。与苏亚雷斯 - 库尔茨和帕克的报告相反，双刺激并未使双折射信号与钙释放分离。这一结果支持了以下假设：早期大双折射信号是骨骼肌兴奋 - 收缩偶联过程中从肌浆网释放钙的内在指标。
