DRUG-INDUCED SECRETION OF CATECHOLAMINES BY THE PERFUSED ADRENAL GLAND OF THE DOG DURING NICOTINE BLOCKADE

¹ Department of Pharmacology, West Virginia University Medical Center, Morgantown, West Virginia

Isolated adrenal glands of dogs were perfused through the adrenolumbar vein with an oxygenated Krebs-Ringer solution at room temperature. Catecholamines in the effluent from the glands were assayed continuously with an automated trihydroxyindole method. After a series of 55 injections of 500 µg of nicotine at 100-second intervals, the release of catecholamines from the glands in response to injections of the nicotinic agents dimethyiphenylpiperazinium and tetramethylammonium was greatly reduced. The postnicotine responses to injections of acetyicholine, KC1 and the nonnicotinic agents, piocarpine, angiotensin, bradykinin and histamine were potentiated. The potentiated responses were generally biphasic, consisting of an initial sharp peak with the maximum output quickly attained, followed by a prolonged second component. The injection of hexamethonium into the adrenal during the potentiated secretory responses blocked the enhanced release of catecholamines.