BRAIN ANGIOTENSIN-II CONTRIBUTES TO THE DEVELOPMENT OF HYPERTENSION IN DAHL-IWAI SALT-SENSITIVE RATS

Objective: To examine the role of brain angiotensin II in the developm ent of salt-induced hypertension in Dahl-lwai salt-sensitive (DIS) rat s. Methods: Male DIS and Dahl-lwai salt-resistant (DIR) rats aged 5 or 6 weeks were implanted with an intracerebroventricular cannula, and e ither chronic intracerebroventricular infusion of 5 mu g/day CV-11974, a non-peptide type-1 angiotensin II receptor antagonist or artificial cerebrospinal fluid (aCSF) was started. The rats were fed a diet cont aining 8% sodium chloride. Results: On day 11 or 12 of chronic infusio n, DIS rats given CV-11974 intracerebroventricularly exhibited a signi ficantly lower mean arterial pressure than DIS rats given aCSF intrace rebroventricularly or intravenous infusion of CV-11974. In DIR rats, i ntracerebroventricular infusion of CV-11974 did not alter the mean art erial pressure. Sodium and water balances were similar in all of the g roups. Plasma vasopressin and noradrenaline levels did not differ amon g the groups, although the plasma renin concentration was significantl y lower in DIS rats given aCSF intracerebroventricularly. Arterial bar oreflex control of heart rate and presser response to intravenous inje ction of phenylephrine were not altered in rats given CV-11974 intrace rebroventricularly. Conclusion: The integrity of the brain renin-angio tensin system is necessary for the development of salt-induced hyperte nsion in DIS rats.