Oota I, Nagai T
Jpn J Physiol. 1976;26(4):385-94. doi: 10.2170/jjphysiol.26.385.
45Ca influx in the intact, the T-disrupted, and the urea-treated or Mn++-treated frog sartorius muscles was measured at rest and during potassium contracture. In the intact muscle, Ca influx increased with the increasing of potassium concentration in the bathing solution, and the time course of the Ca influx showed considerable correspondence with that of the potassium contracture. This increased Ca influx was divided into two components: early rapid Ca influx and late slow Ca influx. The amount of early rapid Ca influx at higher concentrations of potassium occupied about 60% of the total Ca influx. The early rapid Ca influx markedly decreased in the T-disrupted and in the urea-treated or Mn++-treated muscles. On the other hand, the late slow Ca influx and the resting Ca influx in these muscles changed only slightly. These results suggest that the early rapid Ca influx occurs mainly through the membrane of the T-system, particularly at the triadic junctional area of muscle fiber, while the late slow Ca influx and the resting Ca influx occur mainly through the surface membrane.
在静息状态和钾离子收缩期，对完整的、T 系统破坏的、经尿素处理或 Mn++处理的青蛙缝匠肌的 45Ca 内流进行了测量。在完整肌肉中，Ca 内流随着浴液中钾离子浓度的增加而增加，并且 Ca 内流的时间进程与钾离子收缩的时间进程显示出相当的一致性。这种增加的 Ca 内流分为两个部分：早期快速 Ca 内流和晚期缓慢 Ca 内流。在较高钾离子浓度下，早期快速 Ca 内流的量约占总 Ca 内流的 60%。在 T 系统破坏的以及经尿素处理或 Mn++处理的肌肉中，早期快速 Ca 内流显著减少。另一方面，这些肌肉中的晚期缓慢 Ca 内流和静息 Ca 内流仅略有变化。这些结果表明，早期快速 Ca 内流主要通过 T 系统的膜发生，特别是在肌纤维的三联体连接区域，而晚期缓慢 Ca 内流和静息 Ca 内流主要通过表面膜发生。
