Inhibition of β-adrenergic response in cultured epidermal cells by phorbol myristate acetate

Treatment of cultured epidermal cells with the tumor promoter, phorbol myristate acetate (PMA), results in a 75% inhibition of the normal isoproterenol stimulated 7-fold increase in cAMP accumulation. Maximum inhibition occurred 3 h after PMA treatment. The effect of phorbol ester on the beta-adrenergic system in mouse epidermis thus appears to be due to its action on the epidermal cell membrane and does not require mediation by macrophages.