Cytochrome c protein synthesis rate in rat skeletal muscle.
Endurance training is associated with increases in mitochondrial density, of which cytochrome c protein is an index. Increases in the synthesis rates of cytochrome c protein in skeletal muscle during endurance training have been inferred (Biochem. Biophys. Res. Commun. 66: 173, 1975; J. Biol. Chem. 252: 416, 1977). One purpose of the present study was to test these indirect approximations with direct measurements of the synthesis rates of cytochrome c protein in skeletal muscles postexercise. No change in the fractional synthesis rate of cytochrome c was detected in the red quadriceps muscle of rats either 2-7 h after a 104-min run on a motor-driven treadmill or 17-22 h after the final bout of 4 days of running 100 min/day. If the 16% increase in cytochrome c protein concentration in the red quadriceps muscle on the 5th day of training is used to calculate the nanomoles of cytochrome c synthesized per gram of wet muscle weight, the normalized rate of cytochrome c protein synthesis is increased 29% on the 5th day of training. The observation of no significant alteration in cytochrome c mRNA in the red quadriceps muscle of rats during the 1st wk of training implies that the initial increase in the synthesis rate of cytochrome c protein normalized per unit of muscle mass during treadmill training is likely to occur at a translational or posttranslational step. These results suggest that the control of increased cytochrome c expression in skeletal muscle during exercise training involves a complex mechanism.
Booth
F W
FW
Department of Physiology and Cell Biology, University of Texas Medical School, Houston 77225.
D000818:Animals; D015152:Blotting, Northern; D002950:Citrate (si)-Synthase / Q000378:metabolism; D003574:Cytochrome c Group / Q000096:biosynthesis*; D005260:Female; D008931:Mitochondria, Muscle / Q000378:metabolism; D009132:Muscles / Q000201:enzymology*; D009693:Nucleic Acid Hybridization; D010805:Physical Conditioning, Animal; D012333:RNA, Messenger / Q000096:biosynthesis; D012356:RNA, Transfer, Leu / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D003574:Cytochrome c Group; D012333:RNA, Messenger; D012356:RNA, Transfer, Leu; D002950:Citrate (si)-Synthase