10Hz慢性电刺激后兔胫前肌的产力及工作能力

Power production and working capacity of rabbit tibialis anterior muscles after chronic electrical stimulation at 10 Hz.

作者信息

Jarvis J C

机构信息

Department of Human Anatomy and Cell Biology, University of Liverpool.

出版信息

J Physiol. 1993 Oct;470:157-69. doi: 10.1113/jphysiol.1993.sp019852.

DOI:10.1113/jphysiol.1993.sp019852

PMID:8308723

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1143911/

Abstract

The muscles of the distal anterior compartment of the left hindlimb of rabbits were subjected to continuous indirect electrical stimulation at 10 Hz for periods of up to 12 weeks by means of an implantable stimulator. 2. The maximum shortening velocity (Vmax) and the velocity for maximum power production in single contractions (Vopt) were reduced to 42% and 32% of control values respectively after 12 weeks of stimulation. The rate of change of these parameters was greatest between the second and sixth week of stimulation. These changes, it is suggested, reflect the documented time course of the replacement of fast with slow isoforms of myosin. 3. The reductions in force production and speed of the stimulated muscles combined to produce a marked, progressive decline in the maximum power produced in single contractions. After 8 weeks of stimulation, the maximum power output had fallen to less than 10% of the control value. 4. The fatigue resistance of the stimulated and control muscles was tested over several hours of cyclical shortening contractions designed to elicit an initial power output of 10 W kg-1 with the muscles set to contract at Vopt. This level of work output represented about 1.6% (control) and 25% (12-week-stimulated) of the absolute maximum power output achieved during single contractions. 5. Despite the large reduction in the maximum power output of single contractions, the stimulated muscles showed less than 10% reduction in their power output during the fatigue tests over periods of up to 7 h. The control muscles showed a 70% reduction over the same period. There was no difference in the fatigue resistance under this protocol between muscles stimulated for 2 weeks and those stimulated for longer periods. Transformation of myosin isoforms, which is known to occur later than 2 weeks after the start of stimulation, is not necessary for the induction of this degree of fatigue resistance.

摘要

通过植入式刺激器，对兔左后肢远端前侧肌间隔的肌肉以10赫兹的频率进行长达12周的持续间接电刺激。2. 刺激12周后，单次收缩时的最大缩短速度（Vmax）和最大功率产生速度（Vopt）分别降至对照值的42%和32%。这些参数的变化率在刺激的第二至六周最大。有人认为，这些变化反映了已记录的肌球蛋白快速异构体被慢速异构体取代的时间进程。3. 受刺激肌肉的力量产生和速度下降，共同导致单次收缩中产生的最大功率显著且逐渐下降。刺激8周后，最大功率输出已降至对照值的10%以下。4. 在数小时的周期性缩短收缩过程中测试受刺激肌肉和对照肌肉的抗疲劳能力，旨在使肌肉以Vopt收缩时产生10 W kg-1的初始功率输出。这种工作输出水平分别约为单次收缩期间达到的绝对最大功率输出的1.6%（对照）和25%（刺激12周）。5. 尽管单次收缩的最大功率输出大幅降低，但在长达7小时的疲劳测试期间，受刺激肌肉的功率输出降低不到10%。对照肌肉在同一时期功率输出降低了70%。在该方案下，刺激2周的肌肉和刺激更长时间的肌肉之间的抗疲劳能力没有差异。肌球蛋白异构体的转变，已知在刺激开始后2周后才会发生，对于诱导这种程度的抗疲劳能力不是必需的。