Redox environment metabolomic evaluation (REME) of the heart after myocardial ischemia/reperfusion injury

Myocardial ischemia/reperfusion injury (MIRI) is closely related to oxidative stress. However, the redox environment of the heart has not been evaluated thoroughly after MIRI, which limits precise redox intervention. In this study, we developed the redox environment metabolomic evaluation (REME) method to analyze the redox metabolites of the heart after MIRI. Based on the targeted metabolomics strategy, we established a detection panel for 22 redox-related molecules, including the major redox couples nicotinamide adenine dinucleotide (NADH/NAD+), nicotinamide adenine dinucleotide phosphate (NADPH/NADP+), and glutathione/glutathione disulfide (GSH/GSSG), reactive oxygen and nitrogen species-related molecules, and some lipid peroxidation products. The high sensitivity and specificity of the method make it suitable for evaluating the endogenous redox environment. The REME method showed that the heart tissue in a MIRI mouse model had a different redox profile from that in the control group. Different redox species changed in different ways. The ratios of GSSG/GSH and NADP+/NADPH increased, but the levels of both NAD+ and NADH decreased in the risk area of the infarcted heart after reperfusion. In addition, some reactive nitrogen species-related metabolites (tetrahydrobiopterin, arginine, and S-nitrosoglutathione) decreased and some lipid peroxides (4-hydroxy-2-nonenal, 4-hydroxy-2-hexenal, and benzaldehyde) increased. The redox metabolites GSH, GSSG, NADPH, NAD+, S-nitrosoglutathione, arginine, and tetrahydrobiopterin had a positive correlation with the ejection fraction and a negative correlation with the level of lactate dehydrogenase in plasma. In summary, we achieved a comprehensive, systemic understanding of the changes in the redox environment after MIRI. Our REME method could be used to evaluate the redox environment in other processes.