1A-779 attenuates angiotensin-(1–7) depressor response in salt-induced hypertensive rats

Chronic infusion of angiotensin-(1–7) [Ang-(1–7)] lowers blood pressure in salt-induced and spontaneously hypertensive (SHR) rats. In the present study, we have examined the acute effect of Ang-(1–7) in salt-induced hypertension using Dahl salt-sensitive rats placed on low (0.3%) or high (8.0% NaCl) salt diets for 2 weeks. Rats fed a high salt diet showed a greater rise in BP than those fed a low salt diet. Ang-(1–7) (24 μg/kg) reduced mean arterial pressure (MAP), enhanced the release of prostacyclin and nitric oxide, and suppressed thromboxane A 2 levels. A-779 (48 μg/kg, i.v), a selective Ang-(1–7) antagonist, partially blocked these effects of Ang-(1–7). The Ang-(1–7)-induced depressor response observed in these animals was related to an increase in vasodilatory prostanoids, a decrease in the constrictor prostanoid thromboxane A 2, and an increase in nitric oxide levels in both plasma and isolated aortic rings.