Yamada Kazuhiro
Department of Neurophysiology, University of Oita Faculty of Medicine, Yufu, Oita, 879-5593, Japan.
J Physiol Sci. 2017 Jan;67(1):19-43. doi: 10.1007/s12576-016-0470-3. Epub 2016 Jul 13.
Knowledge accumulated in the field of energetics of muscle contraction has been reviewed in this article. Active muscle converts chemical energy into heat and work. Therefore, measurements of heat production and mechanical work provide the framework for understanding the process of energy conversion in contraction. In the 1970s, precise comparison between energy output and the associated chemical reactions was performed. It has been found that the two do not match in several situations, resulting in an energy balance discrepancy. More recently, efforts in resolving these discrepancies in the energy balance have been made involving chemical analysis, phosphorus nuclear magnetic resonance spectroscopy, and microcalorimetry. Through reviewing the evidence from these studies, the energy balance discrepancy developed early during isometric contraction has become well understood on a quantitative basis. In this situation energy balance is established when we take into account the binding of Ca to sarcoplasmic proteins such as troponin and parvalbumin, and also the shift of cross-bridge states. On the other hand, the energy balance discrepancy observed during rapid shortening still remains to be clarified. The problem may be related to the essential mechanism of cross-bridge action.
本文回顾了肌肉收缩能量学领域积累的知识。活跃的肌肉将化学能转化为热量和功。因此，产热和机械功的测量为理解收缩过程中的能量转换过程提供了框架。在20世纪70年代，对能量输出与相关化学反应进行了精确比较。结果发现在几种情况下两者不匹配，导致能量平衡差异。最近，人们通过化学分析、磷核磁共振光谱和微量量热法等方法努力解决这些能量平衡差异。通过回顾这些研究的证据，等长收缩早期出现的能量平衡差异已在定量基础上得到很好的理解。在这种情况下，当我们考虑到钙与肌钙蛋白和小清蛋白等肌浆蛋白的结合以及横桥状态的转变时，能量平衡就建立了。另一方面，快速缩短过程中观察到的能量平衡差异仍有待阐明。这个问题可能与横桥作用的基本机制有关。
