Morrison P R, Biggs R B, Booth F W
Department of Physiology and Cell Biology, University of Texas Medical School, Houston 77225.
Am J Physiol. 1989 Nov;257(5 Pt 1):C936-9. doi: 10.1152/ajpcell.1989.257.5.C936.
The purpose of the study was to determine whether daily running durations that were 7-14% of the durations employed in the chronic stimulation protocols (consisting of 24 h of daily indirect electrical stimulation of skeletal muscles) still resulted in increases in a mitochondrial protein mRNA. Adult female rats were run 100 min/day on motor-driven treadmills for 2 wk. Documentation that rats underwent the stated training program was obtained by a 30-41% increase in citrate synthase activity in hindlimb muscles after 2 wk of the training. Cytochrome c mRNA was increased 17-56% in hindlimb muscles after the 2-wk training program. Thus shorter durations of exercise (100 min/day rather than 24 h/day) can increase cytochrome c mRNA. alpha-Actin mRNA increased 61-62% in fast-twitch muscles in the hindlimbs of the same rats that underwent the 2 wk of run training but did not increase in the predominantly slow-twitch soleus muscle. The increase in alpha-actin mRNA was unexpected, since it is well known that this type of physical exercise does not increase the size of fast-twitch skeletal muscle.
本研究的目的是确定每日跑步时长占慢性刺激方案（包括每日对骨骼肌进行24小时间接电刺激）时长的7%-14%时，是否仍会导致线粒体蛋白mRNA增加。成年雌性大鼠在电动跑步机上每天跑步100分钟，持续2周。通过训练2周后后肢肌肉中柠檬酸合酶活性提高30%-41%，证明大鼠接受了所述训练方案。经过2周训练方案后，后肢肌肉中的细胞色素c mRNA增加了17%-56%。因此，较短时长的运动（每天100分钟而非每天24小时）可增加细胞色素c mRNA。在接受了2周跑步训练的同一批大鼠的后肢快肌中，α-肌动蛋白mRNA增加了61%-62%，但在主要为慢肌的比目鱼肌中未增加。α-肌动蛋白mRNA的增加出乎意料，因为众所周知，这种类型的体育锻炼不会增加快肌骨骼肌的大小。
