Hydrogen Sulfide Improves Myocardial Remodeling via Downregulated Angiotensin Ⅱ/AT1R Pathway in Renovascular Hypertensive Rats

Abstract

Background: Hydrogen sulfide (H₂S) is an important endogenous gaseous transmitter in many physiological functions. Plasma H₂S decreased, and angiotensin II (Ang II) type 1 receptor (AT1R) increased in the myocardial tissues in 2-kidney 1-clip (2K1C) rats than in normotensive rats. Accumulating evidences suggest that H₂S inhibited Ang II/AT1R pathway to regulate cardiovascular function. Therefore, we hypothesized that H₂S may exert beneficial effects on myocardial remodeling in 2K1C rat models of renovascular hypertension.

Methods and results: Sodium hydrosulfide (NaHS, 56 µmol/kg/day) was administered intraperitoneally to the rats from the 7th day after 2K1C operation. Systolic blood pressure was significantly increased from the first week after the operation and was lowered after NaHS treatment for 4 weeks. H₂S could also inhibit the ratio of left ventricle and septum weight to body weight, improve cross-sectional area, and ameliorate ventricular dysfunction. Additionally, the protein expression of AT1R and Ang II serum content were downregulated, whereas superoxide dismutase (SOD) protein was upregulated in 2K1C rats by NaHS treatment for 4 weeks. Furthermore, the reactive oxygen species level and AT1R protein were increased, whereas SOD protein was decreased in cardiomyocytes treated with Ang II compared with the control group. NaHS could reverse these changes. Losartan and N-acetylcysteine could also reverse Ang II-induced changes.

Conclusions: The protective effect of H₂S is attributable to the suppression of oxidative stress. This process involves the inhibition of the Ang II/AT1R pathway and upregulation of antioxidant enzymes in 2K1C rats.

Keywords: angiotensin II type 1 receptor; blood pressure; hydrogen sulfide; hypertension; myocardial remodeling; reactive oxygen species..