期刊
JOURNAL OF MUSCLE RESEARCH AND CELL MOTILITY
卷 33, 期 5, 页码 313-325出版社
SPRINGER
DOI: 10.1007/s10974-012-9307-8
关键词
Lengthening muscle force; Temperature effects; Force-velocity relation; Thermodynamics
类别
资金
- Wellcome Trust
The aim of the present study was to examine the temperature dependence of active force in lengthening and shortening muscle. Experiments were done, in vitro, on bundles of intact fibres (fibre length L-0 similar to 2 mm; sarcomere length similar to 2.5 mu m) isolated from a rat fast muscle (flexor hallucis brevis) and a ramp length change of 5-7 % L-0 was applied on the plateau of an isometric tetanic contraction. Ramp lengthening increased and ramp shortening decreased the muscle tension to new approximately steady levels in a velocity-dependent way. The isometric tension and the lower steady tension reached at a given shortening velocity, increased with warming from 10 to 35 A degrees C and the relation between tension and reciprocal absolute temperature was sigmoidal. However, the tension-temperature curve of shortening muscle was sharper and shifted to higher temperature with increased velocity. In contrast, the enhanced steady tension during lengthening at a given velocity was largely temperature-insensitive within the same temperature range; we hypothesize that the tension-temperature curve may be shifted to lower temperatures in lengthening muscle. Consequently, when normalised to the isometric tension at each temperature, the tension during lengthening at a given velocity decreased exponentially with increase of temperature. The residual force enhancement that remains after ramp lengthening showed a similar behaviour and was markedly reduced in warming from 10 to 35 A degrees C. The findings are consistent with the thesis that active force generation in muscle is endothermic and strain-sensitive; during shortening with a faster crossbridge cycle it becomes more pronounced, but during lengthening it becomes depressed as the cycle slows in a velocity-dependent way. The residual force enhancement may be caused by the same process in addition to non-crossbridge mechanism(s).
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据