Plasma calcitonin gene-related peptide and atrial natriuretic peptide levels during resection of pheochromocytoma.

Calcitonin gene-related peptide (CGRP) and atrial natriuretic peptide (ANP) are potent hypotensive agents. To determine if they play a counterregulatory role in catecholamine excess in patients with pheochromocytoma, plasma levels were measured in four patients undergoing resection of sporadically occurring tumors. Each patient was prepared with phenoxybenzamine hydrochloride (Dibenzyline); two patients also received propranolol. Blood was obtained for plasma levels of epinephrine, norepinephrine, CGRP, and ANP at induction of anesthesia, skin incision, tumor manipulation, tumor removal, and 24 hours after operation. Baseline plasma norepinephrine and epinephrine levels were markedly elevated and increased significantly with tumor manipulation and decreased significantly 24 hours after operation. CGRP and ANP levels were slightly elevated throughout but did not change significantly with tumor manipulation or early after tumor resection. Circulating CGRP and ANP do not appear to have an acute counterregulatory role in catecholamine excess in patients with pheochromocytoma but may exert some influence on postoperative hypotension after tumor removal.