title: Cytochrome c protein-synthesis rates and mRNA contents during atrophy and recovery in skeletal muscle.
abstract: It is known that immobilization of the rat hindlimb by plaster casting leads to muscle atrophy and loss of muscle protein. In the present study, immobilization of the rat hindlimb for 6 h resulted in a significant 27% decrease in the absolute rate of cytochrome c synthesis in the red quadriceps muscle, without any change in the relative amount of cytochrome c mRNA. Cytochrome c mRNA in normal red quadriceps muscle was observed to be of four different lengths (1400, 1050, 650 and 580 bases). After 7 days of immobilization, the absolute rate of cytochrome c synthesis remained depressed and cytochrome c mRNA decreased by 40%; each of the cytochrome c mRNAs decreased, with a preferential disappearance of the 1050- and 1400-base lengths. Immobilization was ended on day 7, and the atrophied muscle was allowed to recover. At day 4 of recovery, the absolute rate of cytochrome c synthesis was 92% higher and the amount of cytochrome c mRNA had returned to control values. The abundances of the 1050- and 1400-base cytochrome c mRNAs had increased more than the shorter cytochrome c mRNAs, so that they were higher than control values. It appears that acute decreases in contractile activity of the red quadriceps muscle alter cytochrome c synthesis rates via translational or post-translational mechanisms, whereas chronic periods of modified contractile activity alter its synthesis rate via pre-translational mechanisms.
mesh_terms: D000818:Animals; D003574:Cytochrome c Group / Q000096:biosynthesis*; D005260:Female; D009119:Muscle Contraction; D009124:Muscle Proteins / Q000096:biosynthesis*; D009132:Muscles / Q000378:metabolism; D009133:Muscular Atrophy / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D003574:Cytochrome c Group; D009124:Muscle Proteins; D012333:RNA, Messenger