Enzymatic and genetic adaptation of soleus muscle mitochondria to physical training in rats.
To evaluate the effects of physical training on mitochondrial gene expression and mitochondrial biogenesis in slow-twitch muscle, adult female Sprague-Dawley rats were trained for 3, 6, and 12 wk by running on a motor-driven treadmill (speed of 25 m/min and duration of 90 min/day, 5 days/wk), and the activities of citrate synthase, ubiquinol-cytochrome-c oxidoreductase, cytochrome oxidase, mitochondrial cytochrome b mRNA (by Northern blot analysis), and mitochondrial DNA (by slot-blot and Southern blot analyses) were measured in rat soleus muscle. A DNA probe for detection of mitochondrial mRNA and DNA was prepared from a 1,500-bp fragment of human mitochondrial DNA that included the coding region of the cytochrome b gene. Training for 3, 6, and 12 wk significantly increased the activities of citrate synthase (31, 28, and 47%, respectively), ubiquinol-cytochrome-c oxidoreductase (61, 63, and 77%, respectively), and cytochrome oxidase (25, 26, and 32%, respectively) in muscle. The concentration of cytochrome b mRNA in the muscle was proportionally elevated with the enzyme activities. On the other hand, the mitochondrial DNA concentration in the muscle was not altered by training for 3 or 6 wk but increased significantly after training for 12 wk (35% in the slot-blot analysis and 31% in the Southern blot analysis). These results suggest that an increase in the oxidative capacity of slow-twitch muscle by the relatively short-term training is regulated at the pretranslational step in mitochondrial protein synthesis but that the increase by the long-term training involves mitochondrial replication.
Murakami
T
T
Department of Bioscience, Nagoya Institute of Technology, Japan.
Shimomura
Y
Y
Fujitsuka
N
N
Nakai
N
N
Sugiyama
S
S
Ozawa
T
T
Sokabe
M
M
Horai
S
S
Tokuyama
K
K
Suzuki
M
M
D000222:Adaptation, Physiological; D000818:Animals; D003573:Cytochrome b Group / Q000235:genetics; D004247:DNA / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006614:Hindlimb; D008854:Microscopy, Electron; D008931:Mitochondria, Muscle / Q000201:enzymology / Q000502:physiology*; D015335:Molecular Probes; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000378:metabolism / Q000648:ultrastructure; D010805:Physical Conditioning, Animal; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D003573:Cytochrome b Group; D004272:DNA, Mitochondrial; D015335:Molecular Probes; D009124:Muscle Proteins; D012333:RNA, Messenger; D004247:DNA