Daily running for 2 wk and mRNAs for cytochrome c and alpha-actin in rat skeletal muscle.
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.
Morrison
P R
PR
Department of Physiology and Cell Biology, University of Texas Medical School, Houston 77225.
Biggs
R B
RB
Booth
F W
FW
D000199:Actins / Q000235:genetics*; D000818:Animals; D003574:Cytochrome c Group / Q000235:genetics*; D005260:Female; D006614:Hindlimb; D009132:Muscles / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D010805:Physical Conditioning, Animal; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D013997:Time Factors
D000199:Actins; D003574:Cytochrome c Group; D012333:RNA, Messenger; D012313:RNA