Effects of cross-bridge compliance on the force-velocity relationship and muscle power output.
Effects of cross-bridge compliance on the force-velocity relationship and muscle power output.
复制标题
DOI：
10.1371/journal.pone.0190335
复制
发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Tanner BCW
中科院分区：
文献类型：
--
作者：
Fenwick AJ;Wood AM;Tanner BCW
肌肉通过ATP水解利用化学能产生力量和动力。在向心性收缩（缩短）期间，肌肉产生的力量比等长收缩小，但随着缩短速度的增加，消耗的能量更大。相反，在偏心肌肉收缩（延长）期间产生更多的力并且消耗更少的能量。力、能量使用和收缩速度之间的这种关系对于理解肌肉效率具有重要意义，但这种行为背后的分子机制仍然知之甚少。在这里，我们使用了空间明确的，多丝模型的Ca2+调节力的生产在半肌节模拟力的生产，能量利用，以及绑定的跨桥的数量是如何受到肌节长度的动态变化。这些计算模拟表明，跨桥约束力增加在低速同心和偏心收缩，相比等距收缩。在我们模拟的整个速度范围内，跨桥循环和能量利用（即ATP酶速率）在缩短过程中增加，在延长过程中减少。这些研究结果是一致的芬效应，但产生于速度依赖性跨桥招聘和跨桥循环动力学之间的复杂关系。我们还研究了力的产生，功率输出和能量利用如何随跨桥和肌丝顺应性而变化，这在典型的实验条件下是不可能解决的。这些重要的模拟表明，增加横桥顺应性导致更大的横桥结合和ATP酶活性，但每个横桥和整个肌节产生的力较小。这些数据表明，生产力的效率下降的速度依赖的方式，这种行为是敏感的跨桥顺应性。相比之下，肌丝顺应性对力产生的显着影响，只有在等长收缩期间观察到，这表明肌丝顺应性的变化可能不会影响功率输出在非等长收缩期间的变化一样大，跨桥顺应性。这些发现推进了我们对肌桥和肌丝特性如何成为肌肉运动过程中收缩效率的速度依赖性变化的基础的理解。
Muscles produce force and power by utilizing chemical energy through ATP hydrolysis. During concentric contractions (shortening), muscles generate less force compared to isometric contractions, but consume greater amounts of energy as shortening velocity increases. Conversely, more force is generated and less energy is consumed during eccentric muscle contractions (lengthening). This relationship between force, energy use, and the velocity of contraction has important implications for understanding muscle efficiency, but the molecular mechanisms underlying this behavior remain poorly understood. Here we used spatially-explicit, multi-filament models of Ca2+-regulated force production within a half-sarcomere to simulate how force production, energy utilization, and the number of bound cross-bridges are affected by dynamic changes in sarcomere length. These computational simulations show that cross-bridge binding increased during slow-velocity concentric and eccentric contractions, compared to isometric contractions. Over the full ranges of velocities that we simulated, cross-bridge cycling and energy utilization (i.e. ATPase rates) increased during shortening, and decreased during lengthening. These findings are consistent with the Fenn effect, but arise from a complicated relationship between velocity-dependent cross-bridge recruitment and cross-bridge cycling kinetics. We also investigated how force production, power output, and energy utilization varied with cross-bridge and myofilament compliance, which is impossible to address under typical experimental conditions. These important simulations show that increasing cross-bridge compliance resulted in greater cross-bridge binding and ATPase activity, but less force was generated per cross-bridge and throughout the sarcomere. These data indicate that the efficiency of force production decreases in a velocity-dependent manner, and that this behavior is sensitive to cross-bridge compliance. In contrast, significant effects of myofilament compliance on force production were only observed during isometric contractions, suggesting that changes in myofilament compliance may not influence power output during non-isometric contractions as greatly as changes in cross-bridge compliance. These findings advance our understanding of how cross-bridge and myofilament properties underlie velocity-dependent changes in contractile efficiency during muscle movement.
登录
查看更多内容
影响因子：
2.7
作者：
Hancock, WO;Huntsman, LL;Gordon, AM
通讯作者：
Gordon, AM
影响因子：
5.5
作者：
Fenn, WO;Marsh, BS
通讯作者：
Marsh, BS
DOI：
10.1098/rspb.1938.0050
发表时间：
1938-10-01
期刊：
PROCEEDINGS OF THE ROYAL SOCIETY SERIES B-BIOLOGICAL SCIENCES
影响因子：
--
作者：
Hill, AV
通讯作者：
Hill, AV
DOI：
10.1073/pnas.77.6.3186
发表时间：
1980-01-01
期刊：
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA-BIOLOGICAL SCIENCES
影响因子：
--
作者：
HILL, TL;EISENBERG, E;GREENE, L
通讯作者：
GREENE, L
影响因子：
3.8
作者：
Chase, PB;Macpherson, JM;Daniel, TL
通讯作者：
Daniel, TL