Rome L C
Department of Biology, Leidy Labs, University of Pennsylvania, Philadelphia 19104, USA.
Comp Biochem Physiol B Biochem Mol Biol. 1998 May;120(1):51-72. doi: 10.1016/s0305-0491(98)00023-6.
Integrative muscle physiology has evolved from black box correlations to an understanding of how muscular systems are designed at the molecular level. This paper traces some of the obstacles facing integrative muscle physiology and some of the intellectual and technological breakthroughs which led to the field's development. The ability to determine (1) which fiber types are active, (2) over what sarcomere lengths and velocities they shorten during locomotion and (3) their respective force-velocity relationships, enabled us to show that many muscular systems are designed so that muscles operate at optimal myofilament overlap and at optimal V/Vmax (where maximum power is generated). The ability to impose the in vivo length change and stimulation pattern on isolated muscle has further showed that fish muscle has a relatively slow relaxation rate, and thus rather than generating maximum power during swimming, the muscle appears designed to generate power efficiently. By contrast, during the single shot jump, frog muscle remains maximally activated during shortening and generates maximum power. Recently biophysical techniques have shown that relaxation rate can be altered during evolution by changing (1) Ca2+ transient duration; (2) Ca(2+)-troponin kinetics, and (3) crossbridge kinetics. New technologies will soon enable us to better appreciate how different animal designs evolved.
整合肌肉生理学已从黑箱相关性发展到对肌肉系统在分子水平上如何构建的理解。本文追溯了整合肌肉生理学面临的一些障碍以及导致该领域发展的一些知识和技术突破。确定（1）哪些纤维类型处于活跃状态，（2）它们在运动过程中在何种肌节长度和速度下缩短，以及（3）它们各自的力 - 速度关系的能力，使我们能够表明许多肌肉系统的设计使得肌肉在最佳肌丝重叠和最佳V/Vmax（产生最大功率的地方）下运作。将体内长度变化和刺激模式施加于分离肌肉的能力进一步表明，鱼类肌肉的松弛速率相对较慢，因此，肌肉在游泳时并非产生最大功率，而是似乎被设计为高效地产生功率。相比之下，在单次跳跃过程中，青蛙肌肉在缩短过程中保持最大激活并产生最大功率。最近，生物物理技术表明，在进化过程中，松弛速率可以通过改变（1）Ca2+瞬变持续时间；（2）Ca(2+)-肌钙蛋白动力学，以及（3）横桥动力学来改变。新技术很快将使我们能够更好地理解不同动物的设计是如何进化的。
