Rall Jack A
Department of Physiology and Cell Biology, Ohio State University, Columbus, OH 43210, USA.
Adv Exp Med Biol. 2005;565:183-92; discussion 379-95. doi: 10.1007/0-387-24990-7_14.
During muscle contraction and relaxation, Ca2+ moves through a cycle. About 20 to 40% of the ATP utilized in a twitch or a tetanus is utilized by the SR Ca2+ pump to sequester Ca2+. Parvalbumin is a soluble Ca2+ binding protein that functions in parallel with the SR Ca2+ pump to promote relaxation in rapidly contracting and relaxing skeletal muscles, especially at low temperatures. The rate of Ca2+ dissociation from troponin C, once thought to be much more rapid than the rate of relaxation, is likely to be similar to the rate of cross-bridge detachment and to the rate of muscle relaxation under some conditions. During the past fifty years, great progress has been made in understanding the Ca2+ cycle during skeletal muscle contraction and relaxation. Nonetheless, there are still mysteries waiting to be unraveled.
在肌肉收缩和舒张过程中，Ca2+经历一个循环。在单收缩或强直收缩中，约20%至40%的ATP被肌浆网Ca2+泵用于隔离Ca2+。小清蛋白是一种可溶性Ca2+结合蛋白，与肌浆网Ca2+泵协同作用，促进快速收缩和舒张的骨骼肌舒张，尤其是在低温下。曾经认为Ca2+从肌钙蛋白C解离的速度比舒张速度快得多，在某些情况下，其可能与横桥解离速度和肌肉舒张速度相似。在过去的五十年里，在理解骨骼肌收缩和舒张过程中的Ca2+循环方面取得了巨大进展。尽管如此，仍有一些谜团有待解开。
