Control of phenylethanolamine N-methyltransferase by glucocorticoids in cultured bovine adrenal medullary cells

Abstract

A procedure for the disaggregation of bovine adrenal medullary cells and a system for their maintenance in primary culture is described. The effect of glucocorticoids on the epinephrine-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT), was examined. The initial level of PNMT activity in cultured cells was maintained by cortisol for 5 days. PNMT activity in untreated cultures declined steadily. After 5 days in culture the response of PNMT activity to cortisol was lost. The EC50 for maintenance of PNMT activity was about 15 ng/ml or 4 x 10(-8) M cortisol. Steroid structural and stereochemical requirements were similar to other glucocorticoid responses. Changes in the functional group or steric configuration of position 11 of cortisol abolished activity. Progesterone inhibited the maintenance of PNMT activity by cortisol in a competitive fashion. It was concluded that the response of PNMT activity to glucocorticoids is specific and sensitive, with strict structural and stereochemical requirements.