EFFECTS OF CHRONIC NICOTINE INGESTION ON PRESSOR RESPONSE TON-NE2RO--ARGININE METHYL ESTER ANDEX VIVOCONTRACTION AND RELAXATION RESPONSE OF AORTA TO-ARGININE

Effects of nitric oxide synthase inhibition on blood vessels were studied in nicotine-treated rats. Male Sprague–Dawley rats drank a nicotine solution with a concentration of 25 or 50 μg/ml for 15 days. The blood pressure and heart rate of chloralose-anaesthetized rats and isolated aortic strip contractions were measured.N^ωNitro--arginine methyl ester (-NAME)-induced hypertension was significantly reduced after chronic nicotine treatment. TheE_maxof contractions of isolated aortic strips to noradrenaline were dose-dependently enhanced by nicotine and the potentiation was abolished by-arginine. The relaxation of aortic strips to acetylcholine was significantly decreased in nicotine-treated rats, whereas-arginine, but not-arginine, reversed this action. Neither nicotine nor-NAME affected the heart rate. The results show that chronic nicotine treatment reduced the pressor response of-NAME.