Taylor T W, Goto Y, Hata K, Takasago T, Saeki A, Nishioka T, Suga H
National Cardiovascular Center Research Institute, Osaka, Japan.
Am J Physiol. 1995 Jun;268(6 Pt 2):H2544-52. doi: 10.1152/ajpheart.1995.268.6.H2544.
Huxley's sliding filament cross-bridge muscle model coupled with parallel and series elastic components was simulated to examine the conflicting reports on the amount of energy saved by quick release at the peak contraction time. Cross-bridge energy utilization was determined by considering the ATP hydrolysis for the cross-bridge cycling. The quick-release cases were simulated by letting the muscle fiber suddenly shorten to the resting fiber length at peak systole, and then the contraction was allowed to continue at the resting length. Simulation results demonstrated that, using realistic parameter values, typically approximately 15% of the muscle fiber energy is used after peak systole (and approximately 30% of the cross-bridge energy), but this is also a function of the muscle fiber properties characterized by cross-bridge association and dissociation rate constants. Increasing the kinetic rate constants, the series elasticity, the initial fiber length, or the time of peak intracellular calcium will increase the amount of energy left, which may explain some of the discrepancies in the literature. Cardiac muscle hypertrophy will increase the fraction of muscle fiber energy left after peak systole to approximately 30%. The strongest indicator of the percent energy left at peak systole was the time the fiber reached peak systole, and as the fiber reached peak systole faster, the amount of energy saved by quick release increased.
对赫胥黎的滑动细丝横桥肌肉模型（结合平行和串联弹性成分）进行了模拟，以研究关于在收缩峰值时间通过快速释放节省的能量数量的相互矛盾的报告。通过考虑横桥循环中的ATP水解来确定横桥能量利用情况。快速释放的情况是通过让肌肉纤维在收缩峰值时突然缩短至静息纤维长度，然后让收缩在静息长度下继续来模拟的。模拟结果表明，使用实际参数值时，通常在收缩峰值后约15%的肌肉纤维能量被消耗（以及约30%的横桥能量），但这也是由横桥结合和解离速率常数表征的肌肉纤维特性的函数。增加动力学速率常数、串联弹性、初始纤维长度或细胞内钙峰值时间会增加剩余能量的数量，这可能解释了文献中的一些差异。心肌肥大将使收缩峰值后剩余的肌肉纤维能量比例增加到约30%。收缩峰值时剩余能量百分比的最强指标是纤维达到收缩峰值的时间，并且随着纤维更快地达到收缩峰值，通过快速释放节省的能量数量增加。
