The role of cyclic AMP in myogenesis.

The effect of exogenously administered cyclic AMP derivatives and of endogenously elevated cyclic AMP levels on the spontaneous fusion of skeletal muscle myoblasts has been investigated. Contrary to earlier reports, cAMP does not appear to have a direct inhibitory effect on the fusion of an established line (L8) of rat myoblasts. Similarly, cAMP did not block the fusion of primary chick myoblasts. However, fusion of the rat myoblasts was prevented when the cAMP induced inhibition of growth prevented the cells from reaching the "critical" cell density necessary for fusion.