Gilbert S H
J Muscle Res Cell Motil. 1986 Apr;7(2):115-21. doi: 10.1007/BF01753412.
Heat rate and tension were measured during the steady state of isovelocity shortening in frog sartorius muscles at two speeds (7.5 and 2.0 mm s-1) through two ranges of the length-tension curve: 1.11 to 1.01 L0 and 1.01 to 0.91 L0. Both heat rate and mechanical power were higher at short length than at long length. The ratio of mechanical power to total energy rate was smaller at short length. The difference in heat rates in the two length ranges was greatest during shortening at 7.5 mm s-1 and least during isometric contractions. Calculations were made for two extreme interpretations of the results, based on the assumption that 30% of the isometric maintenance heat rate at optimum length is produced by processes related to activation: that all the difference in heat rate results from effects of length on activation processes and that all the difference results from effects on contractile processes. The rate of heat production by activation processes would have to be 1.5 times higher at short than at long length in an isometric contraction, 1.7 times higher during shortening at 2mm s-1 and 2.0 times higher at 7.5 mm s-1 to explain the differences in heat rate. The rate of contractile processes would have to be only 1.2 times higher at short than at long length. The results favour the interpretation that the contractile process itself is sensitive to sarcomere length near the plateau of the length-tension curve.(ABSTRACT TRUNCATED AT 250 WORDS)
在青蛙缝匠肌以两种速度（7.5和2.0毫米/秒）进行等速缩短的稳定状态下，通过长度-张力曲线的两个范围：1.11至1.01L0和1.01至0.91L0，测量了热速率和张力。短长度时的热速率和机械功率均高于长长度时。短长度时机械功率与总能量速率的比值较小。两个长度范围内热速率的差异在7.5毫米/秒缩短时最大，在等长收缩时最小。基于以下假设对结果进行了两种极端解释的计算：即最佳长度下等长维持热速率的30%由与激活相关的过程产生；热速率的所有差异均源于长度对激活过程的影响，以及所有差异均源于对收缩过程的影响。在等长收缩中，激活过程产生热量的速率在短长度时必须比长长度时高1.5倍，在2毫米/秒缩短时高1.7倍，在7.5毫米/秒缩短时高2.0倍，才能解释热速率的差异。收缩过程的速率在短长度时只需比长长度时高1.2倍。结果支持这样一种解释，即收缩过程本身对长度-张力曲线平台附近的肌节长度敏感。（摘要截短于250字）
