Jarvis J C, Mokrusch T, Kwende M M, Sutherland H, Salmons S
Department of Human Anatomy and Cell Biology, University of Liverpool, United Kingdom.
Muscle Nerve. 1996 Nov;19(11):1469-75. doi: 10.1002/(SICI)1097-4598(199611)19:11<1469::AID-MUS11>3.0.CO;2-O.
Several previous studies have failed to demonstrate changes due to chronic stimulation in contractile speed of innervated fast rat muscles, and it has been suggested that the adaptive capacity of skeletal muscle in this species is limited. We have reassessed this contention. Fast muscles of the rat hind limb were stimulated continuously at 10 or 20 Hz for 55-61 days. The maximum shortening velocity of the extensor digitorum longus muscles was reduced to 50% of the control value. The proportion of type 1 fibers increased from 4% in control muscle to 34% in stimulated muscles and there was a corresponding reduction in type 2B/D fibers. The proportion of type 2A fibers after stimulation was similar to that in control muscles. These results, taken together with our published analyses of myosin isoform composition of these muscles, show that the mechanisms that control gene expression in response to activity are not exclusive to larger mammals.
此前的多项研究未能证明慢性刺激会使支配的大鼠快肌收缩速度发生变化，有人认为该物种骨骼肌的适应能力有限。我们重新评估了这一论点。以10或20赫兹的频率持续刺激大鼠后肢的快肌55 - 61天。趾长伸肌的最大缩短速度降至对照值的50%。1型纤维的比例从对照肌肉中的4%增加到受刺激肌肉中的34%，2B/D型纤维相应减少。刺激后2A型纤维的比例与对照肌肉中的相似。这些结果，连同我们已发表的对这些肌肉肌球蛋白同工型组成的分析，表明响应活动控制基因表达的机制并非大型哺乳动物所独有。
