Recently, it has been reported that an alpha-adrenergic antagonist phentolamine inhibits epinephrine-induced platelet aggregation but a beta-adrenergic antagonist propranolol did not. In this study, we examined the effects of alpha- and beta-adrenergic antagonist on cytosolic free calcium movements induced by epinephrine. An alpha-adrenergic antagonist phentolamine was found to inhibit the elevation of cytosolic free calcium concentration induced by epinephrine, while a beta-adrenergic antagonist propranolol had no effect on cytosolic free calcium concentration induced by epinephrine.