A model of stress relaxation in cross-bridge systems: effect of a series elastic element.
A model of stress relaxation in cross-bridge systems: effect of a series elastic element.
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DOI：
10.1152/ajpcell.1993.265.1.c279
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发表时间：
1993-07
期刊：
影响因子：
--
通讯作者：
Y. Luo;R. Cooke;E. Pate
中科院分区：
文献类型：
--
作者：
Y. Luo;R. Cooke;E. Pate
在肌肉力学研究中采用的许多实验方案使用张力瞬变作为基础跨桥动力学中的动力学速率的大小的探针。这些瞬变可能会被存在于纤维内和连接到实验装置的点上的弹性元件所修改。为了更好地理解这种修改的幅度，我们使用计算机模拟来研究作用于连接到弹性元件上的肌动蛋白细丝的交叉桥的预期瞬变。采用A.F.赫胥黎的原始跨桥力学模型(Prog.生物群落。1957年7：255-318)。在达到等长平衡后，通过改变解离速率常数G1，同时保持附着速率常数F1固定，来产生张力瞬变。这减少了连接的、产生力量的交叉桥梁的数量。我们发现，即使每半个肌节存在几个(>；或=2)纳米的串联弹性应变，张力的瞬变也会明显减慢。因此，从机械瞬变中推断出的一些速率常数(例如，由笼形配体诱导的那些)可能低估了跨桥过程的实际动力学速率。
Many experimental protocols employed in the study of muscle mechanics use tension transients as a probe of the magnitudes of the kinetic rates in the underlying cross-bridge dynamics. These transients could potentially be modified by the elastic elements that exist both within the fiber and at the points of attachment to the experimental apparatus. To better understand the magnitude of such modifications, we have used computer simulation to investigate the transients that would be expected for cross bridges acting on an actin filament attached to an elastic element. The original model of cross-bridge mechanics by A.F. Huxley was used (Prog. Biophys. 7: 255-318, 1957). After an isometric equilibrium is achieved, a tension transient is produced by changing the dissociation rate constant, g1, while holding the attachment rate constant, f1, fixed. This decreases the number of attached, force-producing cross bridges. We find that the tension transients are markedly slowed by the presence of even a few (> or = 2) nanometers of series elastic strain per half-sarcomere. Thus some rate constants inferred from mechanical transients (e.g., those induced by caged ligands) may underestimate the actual kinetic rates of the cross-bridge processes.