Lapshina I B, Nasledov G A
Fiziol Zh SSSR Im I M Sechenova. 1981 Aug;67(8):1215-22.
Studies in the frog isolated tonic muscle fibers revealed that change of the external calcium concentration normally has no effect on the magnitude of the potassium and caffeine contractures, whereas in denervated fibers a decrease of successively evoked potassium and caffeine contractures occurs in calcium-free solution. The adaptive relaxation of potassium contracture in denervated fibers accelerates with increase of potassium ions and decelerates with increase of calcium. Analysis of these phenomena suggests that: 1) the intracellular calcium alone participates in activation of contraction of these fibers, and 2) the effect of changes in external calcium concentration on the character of contraction is based on the calcium action upon the cell membrane rather than on changes of its amount.
对青蛙离体强直性肌纤维的研究表明，正常情况下，细胞外钙浓度的变化对钾和咖啡因挛缩的幅度没有影响，而在去神经纤维中，在无钙溶液中，相继诱发的钾和咖啡因挛缩会减小。去神经纤维中钾挛缩的适应性舒张随钾离子增加而加速，随钙增加而减速。对这些现象的分析表明：1）仅细胞内钙参与这些纤维收缩的激活，2）细胞外钙浓度变化对收缩特性的影响基于钙对细胞膜的作用，而非其含量的变化。
