The turnover of lactate dehydrogenase in skeletal muscle of the mouse. Influence of fibre type and exercise regimen.
1. The influence of fibre-type and an exercise regimen on the turnover characteristics of proteins in mouse skeletal muscle has been studied. 2. Exercise induced a weight increase in most individual muscles and a decrease in lactate dehydrogenase activity which was more marked in white muscle than red. The coincident decrease in M-subunit activity was more noticeable in fast-twitch muscles than in slow-twitch types. 3. Exercise caused a considerable and consistent increase in the rate of degradation of total soluble proteins in individual muscles, with turnover being higher in muscles with a high red fibre content. 4. The response of lactate dehydrogenase to exercise varied considerably between individual muscles as indicated by the comparative rate constants for synthesis and degradation. In general, degradation was greater in muscle with a high slow-twitch or red fibre content. 5. Overall, a considerable redistribution of protein resources was observed during this physiological perturbation (exercise) with the main emphasis away from the pool of total soluble protein towards the myofibrillar constituents. Highly individualistic responses in relation to rates of synthesis and degradation were observed for the specific protein, lactate dehydrogenase, in the separate muscle of this animal.
D000205:Actomyosin / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D006168:Guinea Pigs; D006984:Hypertrophy; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D009132:Muscles / Q000201:enzymology* / Q000473:pathology; D009218:Myosins / Q000378:metabolism; D005082:Physical Exertion
D000205:Actomyosin; D007770:L-Lactate Dehydrogenase; D000251:Adenosine Triphosphatases; D009218:Myosins