Gulati J, Babu A
Adv Exp Med Biol. 1984;170:725-9. doi: 10.1007/978-1-4684-4703-3_68.
These studies on intact fibers describe the effects of calcium, ionic strength and volume on the contraction properties. The results provide firm evidence that cell volume affects the speed but not the force. On the other hand, sarcoplasmic ionic strength affects the force development, with no effect on unloaded speed of shortening. These results suggest that there are essential differences in the rate limiting steps for isometric and isotonic properties of the cross-bridge mechanism. The studies at various degrees of activation indicate that Ca acts as a simple "on-off" switch for cross-bridge activation, in intact fibers.
这些对完整纤维的研究描述了钙、离子强度和体积对收缩特性的影响。结果提供了确凿的证据，表明细胞体积影响速度但不影响力量。另一方面，肌浆离子强度影响力量的产生，而对无负荷缩短速度没有影响。这些结果表明，横桥机制的等长和等张特性的限速步骤存在本质差异。在不同激活程度下的研究表明，在完整纤维中，钙作为横桥激活的简单“开-关”开关。
