Effect of creatine on contents of myosin heavy chain and myosin-heavy-chain mRNA in steady-state chicken muscle-cell cultures.
Embryonic-chick muscle cells reach a steady state with respect to protein metabolism after approx. 1 week in cell culture. To determine if this steady state could be altered by the administration of agents that have been reported to stimulate myosin heavy-chain synthesis, 7-day muscle-cell cultures were treated with 0-1 mM-creatine. Incorporation of [3H]leucine into myosin heavy chain was stimulated by 30-40% at the optimum creatine concentration (0.2 mM), but this stimulation was blocked when actinomycin D (10 micrograms/ml) was also present. However, the quantity of myosin-heavy-chain mRNA as measured by hybridization in vitro was only 15% higher in creatine-treated cultures, and was therefore not entirely responsible for the observed effect. It is important to note that creatine only exerted its action on myosin-heavy-chain synthesis rate in steady-state cultures; creatine was ineffective in altering this rate in rapidly differentiating 3-day muscle cultures. Finally, muscle-cell cultures that had been grown for the entire 7-day culture period in the presence of 0.2 mM-creatine were assayed for quantity of myosin heavy chain. Control and creatine-treated cultures contained 12.7 +/- 1.5 and 20.5 +/- 1.8 micrograms/dish respectively. In conclusion, creatine apparently enhances the quantity of myosin heavy chain in steady-state embryonic muscle-cell cultures, but it probably does not mediate regulation of myosin content in adult skeletal muscle.
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo; D003401:Creatine / Q000494:pharmacology*; D003609:Dactinomycin / Q000494:pharmacology; D007930:Leucine / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D009218:Myosins / Q000096:biosynthesis / Q000378:metabolism*; D011132:Polyribosomes / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*
D009124:Muscle Proteins; D012333:RNA, Messenger; D003609:Dactinomycin; D009218:Myosins; D007930:Leucine; D003401:Creatine