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 development of salt-induced hypertension in Dahl-Iwai salt-sensitive (DIS) rats. Methods : Male DIS and Dahl-Iwai salt-resistant (DIR) rats aged 5 or 6 weeks were implanted with an intracerebroventricular cannula, and either chronic intracerebroventricular infusion of 5 μg/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 containing 8% sodium chloride. Results : On day 11 or 12 of chronic infusion, DIS rats given CV-11974 intracerebroventricularly exhibited a significantly lower mean arterial pressure than DIS rats given aCSF intracerebroventricularly or intravenous infusion of CV-11974. In DIR rats, intracerebroventricular infusion of CV-11974 did not alter the mean arterial pressure. Sodium and water balances were similar in all of the groups. Plasma vasopressin and noradrenaline levels did not differ among the groups, although the plasma renin concentration was significantly lower in DIS rats given aCSF intracerebroventricularly. Arterial baroreflex control of heart rate and pressor response to intravenous injection of phenylephrine were not altered in rats given CV-11974 intracerebroventricularly. Conclusion : The integrity of the brain renin-angiotensin system is necessary for the development of salt-induced hypertension in DIS rats.