BackgroundThe clipping of an artery supplying one of the two kidneys (2K1C) activates the renin-angiotensin (Ang) system (RAS), resulting in hypertension and endothelial dysfunction. Recently, we demonstrated the intrarenal beneficial effects of sildenafil on the high levels of Ang II and reactive oxygen species (ROS) and on high blood pressure (BP) in 2K1C mice. Thus, in the present study, we tested the hypothesis that sildenafil improves endothelial function in hypertensive 2K1C mice by improving the NO/ROS balance.Methods2K1C hypertension was induced in C57BL/6 mice. Two weeks later, they were treated with sildenafil (40 mg/kg/day, via oral) or vehicle for 2 weeks and compared with sham mice. At the end of the treatment, the levels of plasma and intrarenal Ang peptides were measured. Endothelial function and ROS production were assessed in mesenteric arterial bed (MAB).ResultsThe 2K1C mice exhibited normal plasma levels of Ang I, II and 1–7, whereas the intrarenal Ang I and II were increased (~35% and ~140%) compared with the Sham mice. Sildenafil normalized the intrarenal Ang I and II and increased the plasma (~45%) and intrarenal (+15%) Ang 1–7. The 2K1C mice exhibited endothelial dysfunction, primarily due to increased ROS and decreased NO productions by endothelial cells, which were ameliorated by treatment with sildenafil.ConclusionThese data suggest that the effects of sildenafil on endothelial dysfunction in 2K1C mice may be due to interaction with RAS and restoring NO/ROS balance in the endothelial cells from MAB. Thus, sildenafil is a promising candidate drug for the treatment of hypertension accompanied by endothelial dysfunction and kidney disease.

The aim of this study was to evaluate the effects of sildenafil on endothelial function (EF) in renovascular hypertension (RH). Male C57BL/6 mice were subjected to unilateral renal artery clipping and 14 days later were administered with sildenafil (40 mg/kg/day) or vehicle. After 14 days, the sildenafil significantly reduced the high blood pressure in the 2K1C mice. Assessment of EF through the vasodilation to acetylcholine in isolated mesenteric resistance vessels showed a significant decrease in the maximum response in 2K1C‐veh (44±3%) and it was repaired in 2K1C‐sil (67±4%). Similarly, the increased vasoconstriction (mmHg) to norepinephrine observed in 2K1C‐veh (162±14) was abolished by sildenafil in 2K1C‐sil (116±9) mice. NADPH blocker apocynin improved the EF in the 2K1C‐veh mice, without effect in the other groups. Sildenafil treatment enhanced plasma and kidney levels of Ang 1‐7 (+46%) and caused a significant reduction in the oxidative stress (TBARS assay) in the mesenteric vessels whem compared 2K1C‐veh. These data led us to conclude that sildenafil has a beneficial effect on endothelial dysfunction and oxidative stress in RH mice. Thus, sildenafil is a promising drug for the treatment endothelial dysfunction in RH. Financial support: FAPES, CNPq and CAPES.

The aim of the present study was to evaluate the beneficial cardiovascular effects of sildenafil treatment on experimental hypertension. Male C57BL/6 mice (n=5‐10) were subjected to 2K1C hypertension. After 14 days, sildenafil (40 mg/kg/day) or vehicle was administrated, during a period of 14 days. At the end of experimental period, animals were anesthetized and catheterized to blood pressure recording and had the mesenteric arteriolar bed removed to vascular function studies (acetylcholine ‐ ACh and norephrine ‐ Nor curves) (Protocol 02/2013‐ CEUA‐EMESCAM). Data are mean ± SEM. One‐way ANOVA was performed, followed by Tukey's post hoc test.*p<0.05 and **p<0.01 vs. 2K1C + vehicle. Sildenafil treatment reduced mean arterial blood pressure (124±2 vs. 112±3* mmHg) and heart rate (577±32 vs. 472±19* bpm) in hypertensive‐treated animals. Endothelial function was impaired in hypertensive animals and was successfully restored by sildenafil (Rmax ACh: 50.5±2% vs. 71.6±3%**). Blockage of nitric oxide production with L‐NAME revealed that the participation of this molecule in ACh‐induced vasodilation was augmented by sildenafil (AUC: 60.6±8 vs. 126.8±24*). Similarly, blockage with indomethacin showed the increased participation of COX‐derived prostanoids in vasodilation of treated animals (AUC: 37.9±9 vs. 95.9±17*). The participation of reactive oxygen species was evaluated by blockage of NADPH oxidase with apocinin and revealed that sildenafil was efficient in reducing oxidative stress (AUC: 94.±7.3 vs. 47.4±10.4*). Furthermore, sildenafil was also successful in reducing hyperactivity to Nor in 2K1C animals (Rmax: 167±8 vs. 117±9** mmHg). Thus, sildenafil can restore endothelial function and reduce blood pressure in experimental hypertension and could be suggested as a novel therapeutic approach while treating hypertensive patients. Grant Funding Source: Supported by: Fapes 54498465; CNPq 476525/2012‐8, 473082/2013‐6; FAPES/CNPq/PRONEX Edital 012/2009

The aim of this study was to evaluate the effects of sildenafil on endothelial function of hypertensive mice. Male C57BL/6 mice (n=3–10) were subjected to renal artery clipping (2K1C). After 14 days, sildenafil (40 mg/kg/day) or vehicle was administrated for 14 days. At the end of the treatment, mice were anesthetized and catheterized to blood pressure recording and had the mesenteric arteriolar bed (MAB) and thoracic aorta (TA) removed to vascular function studies. Data are mean ± SEM. One‐way ANOVA was performed followed by Tukey's post hoc test. Sildenafil caused a significant reduction in the arterial blood pressure in treated mice (126±3 vs. 110±4mmHg). Endothelial dysfunction was observed in MAB of 2K1C mice, but not in the TA and it was restored by sildenafil (Rmax ACh: 44±2.6% vs. 59±4.5%). Ongoing studies are revealing an augmented participation of nitric oxide in this process in treated animals. Similarly, an increased maximal response to an alpha 1‐agonist was observed in MAB but not in TA in 2K1C mice, which was ameliorated by sildenafil (167±8 vs.117±9 mmHg). Both TA and MAB did not show impairment in smooth vascular relaxation to sodium nitroprusside. Thus, our data showed that sildenafil can restore endothelial function in hypertensive mice, which reflects in a significant reduction of arterial hypertension.Financial Support: CNPq (Proc. 302582/2011–8) and FAPES/Universal 012/2011 (Proc. 54498465).