Protein synthesis in bupivacaine (marcaine)-treated, regenerating skeletal muscle

Skeletal muscle regeneration has been induced by injection of the myotoxic drug bupivacaine (Marcaine) into the rat tibialis anterior muscle. Doses of 1.5 and 1.0% wt/vol produce significant levels of muscle regeneration, but these doses also produce large regions of ischemic muscle. Doses of 0.75 and 0.5% bupivacaine are also effective in inducing regeneration and produce little or no ischemia. Regenerating muscle is significantly more active in the incorporation of 35S-methionine into protein than is control muscle, and the activity increase is directly proportional to the bupivacaine dose injected. Polyribosomes were isolated in greater yield from bupivacaine-treated muscles, as compared with control muscles, 5 days postinjection, and were also more active in cell-free protein synthesis than control polysomes. Again, the yield and activity of the muscle polysomes was directly proportional to the bupivacaine concentration used for injection. Polyacrylamide gel electrophoresis of polysomal cell-free reaction mixtures demonstrated the synthesis of a number of myofibrillar proteins.