Alterations in Plasma Norepinephrine Concentration During Surgical Resection of Pheochromocytoma

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Abstract
Using a sensitive and specific radioenzymatic assay, the plasma norepinephrine (NE) concentration was measured in 7 patients with pheochromocytoma, 1 patient with bilateral adrenal medullary hyperplasia, 1 patient with a retroperitoneal paraganglioma and 2 patients undergoing bilateral adrenalectomies for palliation of metastatic breast carcinoma. Surgical manipulation of the pheochromocytomas resulted in striking increases in plasma NE concentration with concomitant increases in blood pressure. There were small or no changes in the patients'' plasma NE and blood pressure during resection of the normal adrenal glands, the adrenal glands with medullary hyperplasia or the retroperitoneal paraganglioma. Plasma dopamine-.beta.-hydroxylase (DBH) was measured in 1 patient with pheochromocytomas and the patient with medullary hyperplasia. There was no change in plasma DBH in either patient, supporting the concept that exocytosis is not the primary mechanism for catecholamine secretion from pheochromocytomas. Enflurane is an excellent general anesthetic for the resection of pheochromocytomas, and sodium nitroprusside (rather than phentolamine) may be the agent of choice for the management of the hypertensive episodes that occur during surgical manipulation of pheochromocytomas.