EXOGENOUS HYDROGEN SULFIDE ATTENUATES OXIDATIVE STRESS IN SPONTANEOUSLY HYPERTENSIVE RATS

Vascular oxidative stress occurs in hypertensive states and the potential role of antihypertensive drugs as antioxidants is currently under review. Hydrogen sulfide (H₂S) is a recently recognized member of gasotransmitters, which may act to decrease blood pressure in experimental hypertension. The present study evaluated the antioxidant potential of hydrogen sulfide in SHR. NaHS, donor of H₂S, was subjected to a series of in vitro tests to evaluate its antioxidant capacity. For in vivo study Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) were divided in 4 groups namely WKY control (I), WKY-NaHS treated (II), SHR control (III) and SHR-NaHS treated (IV). Groups II and IV received NaHS, 56 µM/kg i.p. daily for 4 weeks. Blood pressure, renal cortical blood perfusion and pulse wave velocity were measured in acute studies. Oxidative and antioxidant markers from plasma were measured at the end of 4 weeks. In vitro, NaHS was found to be a free radical scavenger, reductant and inhibitor of lipid peroxidation. In vivo, the SHR control rats had higher blood pressure, lower renal cortical blood perfusion, lower H₂S and nitric oxide (NO) in plasma and oxidative stress than compared to the WKY control as evidenced by decreased superoxide dismutase, glutathione and total antioxidant, and increased malondialdehyde plasma levels. NaHS treatment reduced blood pressure, increased renal cortical blood perfusion and increased H₂S and NO plasma levels, and up-regulated the antioxidant defences in SHR-NaHS treated rats. The findings of this study suggest that the administration of NaHS not only reduces the blood pressure but also attenuates the oxidative stress in SHR.