Introduction: Renin angiotensin system has an important role in blood pressure and renal functions. Active angiotensin-converting enzyme 2 converts angiotensin I into angiotensin-(1-7) which is a vasodilator hormone and interacts with nitric oxide changes as well as other angiotensin II receptors. In this study we evaluated the role of Mas receptor antagonist (A779) and renal perfusion pressure (RPP) on serum nitric oxide metabolite (nitrite) concentration when angiotensin II receptors (AT1R & AT2R) were blocked. Methods: After angiotensin II receptors blockage in anesthetized male and female rats, RPP was maintained at two levels 80 & 100 mmHg by occluder around aorta above the renal arteries, and the effects of placebo and A779 on concentration of serum nitrite level were studied. Results: The results showed that when angiotensin II receptors were blocked, the serum level of nitrite in both sexes, was not dependent on angiotensin-(1-7) receptor and did not change statistically, but by increasing renal perfusion pressure and in the presence of angiotensin-(1-7) receptor the serum level of nitrite increased significantly (p<0.05) in male rats but not in female rats. Conclusion: Using angiotensin II receptors blockades and by increase of RPP, the serum level of nitrite is sexrelated. This study showed the importance of Mas receptor in male sex when AT1R & AT2R were blocked.

Keywords: Angiotensin (1-7), Mas receptor, Angiotensin II receptors, NO

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