the binding of 3h-dihydroergocryptine appears to be specific for alpha-adrenergic receptors , since adrenergic agents displace this radioligand with the following order of potency : phentolamine greater than epinephrine greater than or equal to norepinephrine greater than or equal to isoproterenol = propranolol .
C0014563
epinephrine
C0028351
norepinephrine