Cardiovascular and Metabolic Effects of Adenosine 3′,5′-Monophosphate in vivo

Abstract

CATECHOLAMINES activate the enzyme, adenyl cyclase, which forms cyclic adenosine 3′,5′-monophosphate (3′,5′-AMP) in a variety of animal tissues¹. This reaction system has been thought to control several metabolic processes, including glycogenolysis, steroidogenesis, keto-genesis, lipolysis and antidiuresis^1–8. The positive ino-tropic and chronotropic effects of catecholamines on the heart are generally attributed to catechol interaction with the beta adrenergic receptor site. Rall and Sutherland² and Mayer et al.⁹ have proposed that 3′, 5′-AMP might directly affect cardiac beta receptors by mediating hormone-induced changes in contractile force without necessarily involving glycogenolysis. During the course of investigations in the isolated perfused rat liver, 3′,5′-AMP was observed to induce delayed vasomotor changes unrelated to its glycogenolytic action¹⁰. This suggested that 3′, 5′-AMP might have a direct vascular effect on smooth muscle. Although 3′,5′-AMP produces hypergly-caemia in intact animals^1,10–13, correlation of its metabolic action with possible regulation of cardiac activity has not been previously investigated.