Inhibition of platelet adenylate cyclase by epinephrine requires GTP

Abstract

Introduc~or~Epinephrine and norephaephrine cause aggregation of human piatelets.This effect is blocked by o~-adrenergic blocking agents such as phentolarnine and dihydroergotamJne and, therefore, is assumed to involve a-adrener~c receptors [1--3].Epinephrine is capable of lowering prosta~andin E ~ -stimulated cyclic AMP levels, an effect that involves ~-adrenergic receptors [4--8].