Enhancement of acetylcholine-evoked catecholamine release from perfused dog adrenals by elevating cyclic AMP levels.

Guanylyl-imidodiphosphate, guanosine 5'-tetraphosphate and phosphodiesterase inhibitors, 3-isobutyl-1-methylxanthine and RO 20-1724 significantly increased the basal cAMP output and caused a slight catecholamine (CA) release. These agents accelerated ACh-induced increase in cAMP output followed by a markedly enhanced CA release. Cholera toxin did not cause CA release but markedly enhanced ACh-evoked CA release. These results may suggest that cAMP plays a modulating role in CA release from chromaffin cells.