Sulfur dioxide improves endothelial dysfunction by downregulating the angiotensin II/AT(1)R pathway in D-galactose-induced aging rats

The aim of this study was to investigate the protective effects of sulfur dioxide (SO(2)) on the endothelial function of the aorta in D-galactose (D-gal)-induced aging rats. Sprague Dawley rats were randomized into a D-gal group, a D-gal + SO(2) group and a control group, then injected with D-gal, D-gal + SO(2) donor or equivalent volumes of saline, respectively, for 8 consecutive weeks. After 8 weeks, the mean arterial pressure was significantly increased in the D-gal group, but was lowered by SO(2). SO(2) significantly ameliorated the endothelial dysfunction induced by D-gal treatment. The vasorelaxant effect of SO(2) was associated with the elevated nitric oxide levels and upregulated phosphorylation of endothelial nitric oxide synthase. In the D-gal group, the concentration of angiotensin II in the plasma was significantly increased, but was decreased by SO(2). Moreover, levels of vascular tissue hydrogen peroxide (H(2)O(2)) and malondialdehyde were significantly lower in SO(2)-treated groups than those in the D-gal group. Western blot analysis showed that the expressions of oxidative stress-related proteins (the angiotensin II type 1 receptor (AT(1)R), and nicotinamide adenine dinucleotide phosphate oxidase subunits) were increased in the D-gal group, while they were decreased after treatment with SO(2). In conclusion, SO(2) attenuated endothelial dysfunction in association with the inhibition of oxidative stress injury and the downregulation of the angiotensin II/AT(1)R pathway in D-gal-induced aging rats.