History-dependent mechanical properties of permeabilized rat soleus muscle fibers
History-dependent mechanical properties of permeabilized rat soleus muscle fibers
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DOI：
10.1016/s0006-3495(02)75454-4
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发表时间：
2002-02-01
影响因子：
3.4
通讯作者：
Moss, RL
中科院分区：
文献类型：
--
作者：
Campbell, KS;Moss, RL
对大鼠比目鱼肌通透性肌纤维进行重复的三角长度改变(肌节长度控制下的斜坡式拉伸/释放，0.03/(O)，+/-0.1/(O)S(-1))，以探讨运动后僵硬恢复率是否随钙激活水平的增加而增加。积极收缩的纤维对拉伸表现出特有的张力反应：张力在运动的初始阶段急剧上升，然后略微下降到平台期，在拉伸的其余阶段保持不变。当纤维被拉伸两次时，反应的初始阶段减少了一定程度，这取决于钙激活水平和自第一次运动以来经过的时间。详细的分析揭示了三个新的重要发现。1)硬度和张力恢复率；2)张力平台的相对高度均随钙激活程度的增加而增加。3)在第二次拉伸过程中，高游离钙浓度下的张力平台比低钙浓度下发育得更快。这些发现与跨桥机制是一致的，但表明力产生功率卒中的比率随着细胞内钙离子浓度和跨桥应变的增加而增加。
Permeabilized rat soleus muscle fibers were subjected to repeated triangular length changes (paired ramp stretches/releases, 0.03/(O), +/- 0.1/(O) s(-1) imposed under sarcomere length control) to investigate whether the rate of stiffness recovery after movement increased with the level of Ca2+ activation. Actively contracting fibers exhibited a characteristic tension response to stretch: tension rose sharply during the initial phase of the movement before dropping slightly to a plateau, which was maintained during the remainder of the stretch. When the fibers were stretched twice, the initial phase of the response was reduced by an amount that depended on both the level of Ca2+ activation and the elapsed time since the first movement. Detailed analysis revealed three new and important findings. 1) The rates of stiffness and tension recovery and 2) the relative height of the tension plateau each increased with the level of Ca2+ activation. 3) The tension plateau developed more quickly during the second stretch at high free Ca2+ concentrations than at low. These findings are consistent with a cross-bridge mechanism but suggest that the rate of the force-generating power-stroke increases with the intracellular Ca2+ concentration and cross-bridge strain.