REGULATION BY PHYSICAL-TRAINING OF ENZYME-ACTIVITY AND GENE-EXPRESSION OF BRANCHED-CHAIN 2-OXO ACID DEHYDROGENASE COMPLEX IN RAT SKELETAL-MUSCLE

We examined the effects of short-term (5 weeks) and long-term (12 week s) physical training on actual and total activities, protein content a nd mRNA abundance of branched-chain 2-oxo acid dehydrogenase complex i n rat skeletal muscle. The actual and total activities were significan tly increased similar to 60% and similar to 40%, respectively, by long -term training. No effects of short-term training on activities were o bserved. The increase in the total activity corresponded to increased protein content of the E1 alpha and E2 components of the complex. On t he other hand, mRNA abundance for E1 alpha and E2 were not affected by the training, but that for E1 beta was slightly, but significantly in creased by both short-term and long-term trainings. These divergent al terations of the message levels for the subunits of the complex sugges t that posttranslational regulatory mechanisms determine the amount of the complex in skeletal muscle. Since the complex is located in the m itochondrial matrix space, mitochondrial biogenesis in response to the training was examined by determining the content of mitochondrial DNA in the muscle. The mitochondrial DNA was proportionally increased wit h the total activity as well as the protein content of the complex, su ggesting that expression of branched-chain 2-oxo acid dehydrogenase co mplex in skeletal muscle in response to physical training is associate d with mitochondrial biogenesis.