Is the efficiency of mammalian (mouse) skeletal muscle temperature dependent?
Is the efficiency of mammalian (mouse) skeletal muscle temperature dependent?
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DOI：
10.1113/jphysiol.2010.192799
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发表时间：
2010-10-01
影响因子：
5.5
通讯作者：
Curtin, N. A.
中科院分区：
文献类型：
--
作者：
Barclay, C. J.;Woledge, R. C.;Curtin, N. A.
肌肉中的肌球蛋白横桥将化学能转化为机械能。与使用其他哺乳动物物种的肌肉在体外测量的值相比，报告的人类肌肉中的桥效率值较高。大多数体外肌肉实验都是在低于哺乳动物生理温度的温度下进行的，这增加了人类效率值高于分离制剂的可能性，因为效率取决于温度。本研究的目的是确定温度对离体哺乳动物（小鼠）肌肉效率的影响。测量了等速缩短过程中快肌趾长伸肌 (EDL) 和慢肌比目鱼肌的肌纤维束的功率输出和热量产生。机械效率定义为功率输出与热输出率之比，其中热输出率是功率输出与热输出率之和。实验在 20、25 和 30 摄氏度下进行。EDL 肌肉的最大效率与温度无关； 30 摄氏度时的最高值为 0.31 +/- 0.01 (n = 5)。比目鱼肌制剂的最大效率在 25 和 30 摄氏度时稍稍但显着高于 20 摄氏度； 25°C 时的最大平均值为 0.48 +/- 0.02 (n = 7)。结论是，离体小鼠肌肉的最大机械效率受 20 至 30°C 温度之间的影响很小，并且与离体哺乳动物肌肉相比，温度差异不太可能解释体内人体肌肉相对较高的效率。
Myosin crossbridges in muscle convert chemical energy into mechanical energy. Reported values for crossbridge efficiency in human muscles are high compared to values measured in vitro using muscles of other mammalian species. Most in vitro muscle experiments have been performed at temperatures lower than mammalian physiological temperature, raising the possibility that human efficiency values are higher than those of isolated preparations because efficiency is temperature dependent. The aim of this study was to determine the effect of temperature on the efficiency of isolated mammalian (mouse) muscle. Measurements were made of the power output and heat production of bundles of muscle fibres from the fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus muscles during isovelocity shortening. Mechanical efficiency was defined as the ratio of power output to rate of enthalpy output, where rate of enthalpy output was the sum of the power output and rate of heat output. Experiments were performed at 20, 25 and 30 degrees C. Maximum efficiency of EDL muscles was independent of temperature; the highest value was 0.31 +/- 0.01 (n = 5) at 30 degrees C. Maximum efficiency of soleus preparations was slightly but significantly higher at 25 and 30 degrees C than at 20 degrees C; the maximum mean value was 0.48 +/- 0.02 (n = 7) at 25 degrees C. It was concluded that maximum mechanical efficiency of isolated mouse muscle was little affected by temperature between 20 and 30 degrees C and that it is unlikely that differences in temperature account for the relatively high efficiency of human muscle in vivo compared to isolated mammalian muscles.