Nitric Oxide Synthases Blockade; L-NAME and Estradiol Alter Renal Blood Flow Response to Angiotensin 1-7 in...

Nitric oxide (NO) and angiotensin 1-7 (Ang 17), as components of the renin-angiotensin system (RAS), play key roles in the control of renal circulation. We test the hypothesis that NO synthase (NOS) blockade by L-NAME or estradiol alters the renal blood flow (RBF) response to Ang 1-7 infusion. Female Wistar rats were ovariectomized and assigned into two groups treated with estradiol or vehicle for two weeks. At controlled renal perfusion pressure (RPP), mean arterial pressure (MAP), RBF, and renal vascular resistance (RVR) responses to graded infusion of Ang 1-7 with and without L-NAME were measured. MAP, RPP, and RVR increased and RBF decreased significantly on pretreatment of L-NAME (P<0.05). Estradiol increased the level of nitrite (P<0.05), and during Ang 1-7 infusion, estradiol alone increased the RBF response to Ang 1-7 infusion significantly (P<0.05). However, L-NAME decreased the RBF response to Ang 1-7 significantly (P<0.05) in both vehicle and estradiol-treated groups. Estradiol enhanced the RBF response to Ang 1-7 infusion, which was decreased by L-NAME. This effect of estradiol on RBF response to Ang 1-7 may be modulated via the NO pathway.