The effect of cholera toxin on myogenesis in rat skeletal muscle cultures

Cholera toxin, when added to rat primary embryonic muscle cultures, stimulates intracellular cyclic AMP and cell fusion. The effect on cell fusion can be mimicked by daily addition of dibutyryl cyclic AMP, but not by choleragenoid, which like cholera toxin binds to the ganglioside G_M1, but does not stimulate adenyl cyclase. The effects on fusion of three other agents known to affect intracellular cyclic AMP levels, indomethacin, isobutylmethyl xanthine, and isoproterenol were also studied. It is concluded that intracellular cyclic AMP levels are important in the control of rat skeletal muscle cell fusion.