Hormone responsiveness of adenylate cyclase activity of cultured myogenic cells

We studied the effect of catecholamines on the adenylate cyclase activity of myogenic cells of the L6 line during the differentiation process. The enzyme of mononucleated myoblasts was found to be activated by adrenaline L, noradrenaline L, and to a small extent, by adrenaline D and dihydrocymandelic acid. The adenylate cyclase of the differentiated cells responded to adrenaline L and noradrenaline L but not to adrenaline D or dihydroxymandelic acid. This activation could be inhibited by the addition of DOPA and propranolol, a specific beta adrenergic blocker. alpha adrenergic compounds such as phentolamine did not have any effect. It is concluded that beta adrenergic receptors are present on myogenic cells before and after differentiation.