Antioxidant Effects of Hydrogen Sulfide on Left Ventricular Remodeling in Smoking Rats Are Mediated via PI3K/Akt-Dependent Activation of Nrf2

There is growing evidence that oxidative stress plays critical roles in the pathogenesis of cardiac remodeling. In the present study, we established a rat model of passive smoking and investigated the antioxidant effects of hydrogen sulfide (H2S) on smoking-induced left ventricular remodeling. Cardiac structure and function were evaluated using 2-dimensional echocardiography. Myocardial fibrosis was detected by Masson's trichrome staining and immunohistochemistry. Oxidative stress was assessed by measuring malondialdehyde levels, superoxide dismutase and glutathione peroxidase activities, and reactive oxygen species generation in the myocardium. Neonatal rat cardiomyocytes transfected with specific siRNA and exposed to cigarette smoke condensate and H2S donor sodium hydrosulfide were used to confirm the involvement of Nrf2 and PI3K/Akt signaling in the antioxidant effects of H2S. Our results indicated that H2S could protect against left ventricular remodeling in smoking rats via attenuation of oxidative stress. Moreover, H2S was also found to increase the phosphorylation of Akt and GSK3β and decrease the nuclear expression of Fyn, which consequently leads to nuclear translocation of Nrf2 and elevated expression of HO-1 and NQO1. In conclusion, H2S may exert antioxidant effects on left ventricular remodeling in smoking rats via PI3K/Akt-dependent activation of Nrf2 signaling.