Hydrogen Sulfide Attenuates Myocardial Hypoxia-Reoxygenation Injury by Inhibiting Autophagy via mTOR Activation.

BACKGROUND Autophagy plays a significant role in myocardial ischemia reperfusion (IR) injury. Hydrogen sulfide (H2S) has been demonstrated to protect cardiomyocytes against IR injury, while whether it has anti-autophagy effect has not been known. The aim of this study was to investigate whether H2S regulates autophagy during IR injury and its possible mechanism. METHODS AND RESULTS The cardiomyocytes of neonatal rats were randomized into Con, hypoxia-reoxygenation (HR) and H2S protection groups. The severity of cell injury was evaluated by cell vitality (MTT) and lactate dehydrogenase (LDH) release assays, and autophagy level was evaluated by flow cytometry and the assessment of autophagy-related gene (Atg) expression, such as that of Beclin1 and LC3-II. In response to H2S, Beclin1 and LC3-II protein were found to be down-regulated and p-mTOR protein was found to be up-regulated, together with an increase in cell vitality and a decrease in LDH. Furthermore, to find out whether mTOR was involved in the protective effect of H2S, rapamycin, inhibiter of mTOR, was used with or without applying NaHS and HR. It was found that rapamycin attenuated the myocardiocyte protective effect of H2S. To demonstrate the effect of autophagy during HR injury, the cardiomyocytes were pre-treated with 3-MA, which is an autophagy inhibitor, cell injury was attenuated by 3-MA. CONCLUSIONS H2S plays a myocardial protective role against IR injury by regulating autophagy via mTOR activation.