Hydrogen sulfide protects against hepatocyte cell death and mitochondrial reactive oxygen during hypoxia

Abstract

Hydrogen sulfide (H2S) is an endogenous gas with important physiological functions. The role of H2S in liver injury remains controversial. Exogenous H2S is protective in ischemia/reperfusion and burns, whereas the inhibition of endogenous H2S is protective in sepsis models. We have demonstrated increased oxygen consumption in the liver with low levels of exogenous H2S (<200ìM) via mitochondrial sulfide oxidation but inhibition at higher levels. In vivo H2S infused into the portal vein decreased hepatic tissue PO2. Thus, we hypothesized that H2S contributes to liver injury via exacerbation of cellular hypoxia. To test this, primary rat hepatocytes were subjected to one hour of hypoxia (PO2 < 25 mmHg) in the presence of the slow releasing H2S donor, GYY 4137 (GYY). Hypoxia caused significant cell death in hepatocytes plated at >75% confluence. Contrary to our hypothesis, GYY significantly improved cell viability following hypoxia (84% survival vs. 30% in control, P= 0.0017). Since mitochondrial stress contributes to cell injury, we tested whether GYY decreased mitochondrial reactive oxygen during hypoxia. GYY significantly reduced mitochondrial ROS in hypoxia as visualized by the mitochondrial ROS specific dye Mitosox (TM) (50.3 vs 31.3 units, P=0.006). Thus, H2S protects against hepatocellular injury through a reduction in mitochondrial‐derived reactive oxygen production. Supported by DK38201