Role of calcium and cross bridges in determining rate of force development in frog muscle fibers.
Role of calcium and cross bridges in determining rate of force development in frog muscle fibers.
复制标题
钙和桥在确定青蛙肌肉纤维力量发展速率中的作用。
DOI：
10.1152/ajpcell.1997.272.5.c1664
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Rall,JA
中科院分区：
文献类型：
--
作者：
Wahr,PA;Rall,JA
在 10 摄氏度下，通过光解释放 Ca2+ 从笼中的 Ca2+ 中激活的剥皮青蛙肌肉纤维，检查了 Ca2+ 和产生力的横桥对力发展动力学的影响。等长力发展通过双指数方程拟合，速率为 44.4 s-1 (kc1) 和 6.1 s-1 (kc2)； kc1 与在完整纤维中观察到的力发展速率没有显着差异。由预先存在的次最大力引起的笼中 Ca2+ 的最大激活产生的收缩率与零力最大激活时观察到的收缩率相似。将 Ca2+ 水平降低到最大力发展 50% 的程度，会导致 kc1 降低约七倍，而 kc2 没有变化。部分提取肌钙蛋白 C 仅略微降低 kc1（降低 16%），而通过钒酸盐减少产生力的横桥数量并不会降低 kc1。两种治疗均未改变 kc2。因此，随着 Ca2+ 水平的增加，力量发展的速率急剧增加。
The influence of Ca2+ and force-generating cross bridges on the kinetics of force development was examined in skinned frog muscle fibers activated by photolytic release of Ca2+ from caged Ca2+ at 10 degrees C. Isometric force development was fit by a double exponential equation with rates of 44.4 s-1 (kc1) and 6.1 s-1 (kc2); kc1 was not significantly different from the rate of force development observed in intact fibers. Maximum activation by caged Ca2+ from preexisting submaximal force produced rates of contraction similar to those observed with maximum activation from zero force. Decreasing the Ca2+ level to an extent that resulted in 50% of maximum force development produced an approximately sevenfold decrease in kc1 and no change in kc2. Partial extraction of troponin C reduced kc1 only slightly (by 16%), whereas decreasing the number of force-generating cross bridges by vanadate did not decrease kc1. Neither treatment altered kc2. Thus the rate of force development increases dramatically with increases in Ca2+ level.