Ridgway E B, Gordon A M, Martyn D A
Science. 1983 Mar 4;219(4588):1075-7. doi: 10.1126/science.6823567.
Calcium ions activate muscle contraction. The mechanism depends on the calcium sensitivity of the proteins that regulate contraction. Evidence is presented for the reverse phenomenon, where contraction modulates calcium sensitivity. Increasing the force level increased calcium sensitivity in intact fibers showing that the relation between force and calcium is not unique. A particular calcium concentration can maintain a higher force level than it can create. The results were confirmed in skinned fiber experiments. Transient reduction of the force led to a transient reduction in calcium binding, suggesting a simple mechanism for the hysteresis.
钙离子激活肌肉收缩。其机制取决于调节收缩的蛋白质对钙的敏感性。文中提供了反向现象的证据，即收缩调节钙敏感性。在完整纤维中，增加力的水平会提高钙敏感性，这表明力与钙之间的关系并非唯一。特定的钙浓度能维持比其产生时更高的力水平。这些结果在去膜纤维实验中得到了证实。力的短暂降低导致钙结合的短暂减少，这提示了滞后现象的一种简单机制。
