Dr. V. John Massari I. Alpha Adrenergic Receptor Antagonists A. Introduction 1.
Alpha receptors mediate many important actions of endogenous catecholamines.
The antagonism which is observed in most cases is competitive. C. Cardiovascular Effects of Alpha 1 Antagonists 1. Alpha 1 antagonists block vasoconstriction induced by endogenous catecholamines. The resulting fall in peripheral resistance leads to a fall in mean blood pressure. The magnitude of this effect is dependent upon the degree of sympathetic tone at the time the antagonist is administered.