Vasopressin release by nicotine in the cat

Abstract

Our goal in this study was to examine where nicotine acted on the neurohypophysial release of arginine vasopressin (AVP). In the chamber-isolated, unanesthetized cat, an IV infusion of nicotine (25--50 micrograms/kg/min for 10 min) produced a 54-fold rise in plasma AVP (65 +/- 12.5 microU/ml) and a behavioral sequence of restlessness, ear twitching, salivation, chewing and retching. Chloralose anesthesia and acute surgical preparation increased plasma AVP (9.4 +/- 3.8 microU/ml) 4-times the control level in the unanesthetized state (2.4 +/- 0.1 microU/ml). In the anesthetized cat, an IV infusion of nicotine produced a 140-fold rise in plasma AVP (802.7 +/- 289.0 microU/ml) and a biphasic response in mean arterial blood pressure (MABP) which rose to 32% above control in the first 5 min and fell to 25% below control during the last 5 min. Bilateral surgical section of the carotid sinus and vagus nerves increased plasma AVP (47.6 +/- 25.8 microU/ml) to 5-times the control level in the anesthetized state (9.4 +/- 3.8 microU/ml). In the anesthetized, baroreceptor-denervated cat, an IV infusion of nicotine produced a 3-fold rise in plasma AVP (141.5 +/- 31.3 microU/ml) and a biphasic MABP response. Hypophysectomy abolished the nicotine-induced rise in AVP but did not modify the biphasic MABP response. These data suggest that in the cat nicotine releases AVP from the neurohypophysis by multiple sites of action within the receptive fields of te carotid sinus and vagus nerves and at unknown loci within the central nervous system.