Abstract

A procedure for the assay of the activator of cyclic 3',5'-nucleotide phosphodiesterase is described. The activator is stable at 76° for several minutes; this property was used to isolate and measure the activator in rat adrenal medulla. Doses of carbamylcholine or reserpine that increase the adenosine cyclic 3',5'-monophosphate (cAMP) content of adrenal medulla also increase the content of the phosphodiesterase activator. The increase in cAMP content precedes that of the activator. When the increase of the activator reaches peak values, the cAMP content in medulla is declining. It is suggested that in adrenal medullae of rats the content of cAMP can be regulated by a transsynaptic activation of adenylyl cyclase and by an increase in the potency of the cyclic 3',5'-nucleotide phosphodiesterase activator.