Acetylcholine and cAMP in adrenal medulla: Indirect effect

Abstract

Summary Catecholamine release and cAMP accumulation were studied in bovine adrenal medulla slices in vitro. Acetylcholine (10⁻⁴ M) and salbutamol (10⁻⁶ M) caused increased release of catecholamines and accumulation of cAMP. Incubation in Ca²⁺-free medium abolished the release of catecholamines and the increase of cAMP caused by acetylcholine but not that caused by salbutamol. In a membrane fraction of adrenal medulla acetylcholine (10⁻⁴ M) had no effect on adenylate cyclase activity but salbutamol (10⁻⁶ M) caused substantial activation of adenylate cyclase. It is suggested that acetylcholine has no direct effect on adenylate cyclase or cAMP in adrenal medulla and the accumulation of cAMP observed in slices incubated with acetylcholine is due to the effect of catecholamines, released by acetylcholine, on the medullary cells.