Vasoactive intestinal peptide elevates cyclic AMP levels and potentiates secretion in bovine adrenal chromaffin cells

Vasoactive intestinal peptide (VIP) elevates the levels of cyclic AMP in primary cultures of highly purified chromaffin cells isolated from the bovine adrenal medulla, an effect that is potentiated by inhibitors of cyclic nucleotide phosphodiesterases. This elevation occurs within minutes and elevated levels of cyclic AMP are observed for as long as 24 hr in culture. The half-maximally effective concentration of VIP was approximately 1 microM. The VIP-induced elevation in chromaffin cell cyclic AMP levels was potentiated by simultaneous addition of secretagogues which alone also elevated cellular cyclic AMP levels. VIP alone failed to evoke catecholamine secretion from chromaffin cells, but potentiated potassium-, veratridine-, and nicotine-evoked secretion. Because VIP is found in nerve terminals innervating the adrenal medulla, this neuropeptide appears to be a modulator of chromaffin cell function, possibly via regulation of cyclic AMP levels.