Ruthenium Complex Improves the Endothelial Function in Aortic Rings From Hypertensive Rats

Background:: The endothelium is a monolayer of cells that extends on the vascular inner surface, responsible for the modulation of vascular tone. By means of the release of nitric oxide (NO), the endothelium has an important protective function against cardiovascular diseases. Objective:: Verify if cis- [Ru(bpy)2(NO2)(NO)](PF6)2 (BPY) improves endothelial function and the sensibility of conductance (aorta) and resistance (coronary) to vascular relaxation induced by BPY. Methods:: Normotensive (2K) and hypertensive (2K-1C) Wistar rats were used. For vascular reactivity study, thoracic aortas were isolated, rings with intact endothelium were incubated with: BPY(0.01 to10 µM) and concentration effect curves to acetylcholine were performed. In addition, cumulative concentration curves were performed to BPY (1.0 nM to 0.1 µM) in aortic and coronary rings, with intact and denuded endothelium. Results:: In aorta from 2K-1C animals, the treatment with BPY 0.1µM increased the potency of acetylcholine-induced relaxation and it was able to revert the endothelial dysfunction. The presence of the endothelium did not modify the effect of BPY in inducing the relaxation in aortas from 2K and 2K-1C rats. In coronary, the endothelium potentiated the vasodilator effect of BPY in vessels from 2K and 2K-1C rats. Conclusion:: Our results suggest that 0.1 µM of BPY is able to normalize the relaxation endothelium dependent in hypertensive rats, and the compound BPY induces relaxation in aortic from normotensive and hypertensive rats with the same potency. The endothelium potentiate the relaxation effect induced by BPY in coronary from normotensive and hypertensive rats, with lower effect on coronary from hypertensive rats. Fundamento:: O endotelio e uma monocamada de celulas que se estende sobre a superficie interna vascular, responsavel pela modulacao do tonus vascular. Por meio da liberacao de oxido nitrico (NO), o endotelio tem uma funcao protetora importante contra doencas cardiovasculares. Objetivo:: Verificar se o cis- [Ru (BPY)2 (NO2) (NO)] (PF6) 2 (BPY) melhora a funcao endotelial e a sensibilidade da condutância (aorta) e da resistencia (coronaria) ao relaxamento vascular induzido por BPY. Metodos:: Foram utilizados ratos Wistar normotensos (2K) e hipertensos (2K-1C). Para o estudo de reatividade vascular, as aortas toracicas foram isoladas, os aneis com endotelio intacto foram incubados com: BPY (0,01 a 10 µM) e se realizaram curvas de efeito de concentracao para acetilcolina. Adicionalmente, foram feitas curvas de concentracao cumulativas para BPY (1,0 nM a 0,1 µM) nos aneis aorticos e coronarios, com endotelio intacto e nu. Resultados:: Na aorta de animais 2K-1C, o tratamento com BPY 0,1 µM aumentou a potencia do relaxamento induzido pela acetilcolina e foi capaz de reverter a disfuncao endotelial. A presenca do endotelio nao modificou o efeito da BPY na inducao do relaxamento em aortas de ratos 2K e 2K-1C. Na coronaria, o endotelio potencializou o efeito vasodilatador do BPY em vasos de ratos 2K e 2K-1C. Conclusao:: Nossos resultados sugerem que 0,1 µM de BPY e capaz de normalizar o relaxamento dependente do endotelio em ratos hipertensos, e o composto BPY induz relaxamento na aorta de ratos normotensos e hipertensos com a mesma potencia. O endotelio potencializa o efeito de relaxamento induzido pela BPY em coronarias de ratos normotensos e hipertensos, com menor efeito em coronarias de ratos hipertensos.