INHIBITION OF CATECHOLAMINE SYNTHESIS BY PROADRENOMEDULLIN N-TERMINAL-20-PEPTIDE IN CULTURED BOVINE ADRENAL-MEDULLARY CELLS

In cultured bovine adrenal medullary cells, proadrenomedullin N-termin al 20 peptide (PAMP), at concentrations greater than or equal to 3 mu M, inhibited carbachol-induced [C-14]catecholamine synthesis from [C-1 4]tyrosine. Carbachol-induced activation of tyrosine hydroxylase was a lso attenuated by PAMP. These results suggest that PAMP is a novel end ogenous peptide that regulates catecholamine synthesis via the suppres sion of its rate-limiting enzyme in adrenal medullary cells.