Reduction in hypoxia-reoxygenation-induced myocardial mitochondrial damage with exogenous methane

Albeit previous experiments suggest potential anti-inflammatory effect of exogenous methane (CH₄ ) in various organs, the mechanism of its bioactivity is not entirely understood. We aimed to investigate the potential mitochondrial effects and the underlying mechanisms of CH₄ in rat cardiomyocytes and mitochondria under simulated ischaemia/reperfusion (sI/R) conditions. Three-day-old cultured cardiomyocytes were treated with 2.2% CH₄ -artificial air mixture during 2-hour-long reoxygenation following 4-hour-long anoxia (sI/R and sI/R + CH₄ , n = 6-6), with normoxic groups serving as controls (SH and SH + CH₄ ; n = 6-6). Mitochondrial functions were investigated with high-resolution respirometry, and mitochondrial membrane injury was detected by cytochrome c release and apoptotic characteristics by using TUNEL staining. CH₄ admixture had no effect on complex II (CII)-linked respiration under normoxia but significantly decreased the complex I (CI)-linked oxygen consumption. Nevertheless, addition of CH₄ in the sI/R + CH4 group significantly reduced the respiratory activity of CII in contrast to CI and the CH₄ treatment diminished mitochondrial H₂ O₂ production. Substrate-induced changes to membrane potential were partially preserved by CH₄ , and additionally, cytochrome c release and apoptosis of cardiomyocytes were reduced in the CH₄ -treated group. In conclusion, the addition of CH₄ decreases mitochondrial ROS generation via blockade of electron transport at CI and reduces anoxia-reoxygenation-induced mitochondrial dysfunction and cardiomyocyte injury in vitro.