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Opening of mitochondrial permeability transition pore and Ca2 overload are main contributors to myocardial ischemia-reperfusion injury, which paradoxically causes a wide variety of myocardial damage. We investigated the protective role of a novel necrosis inhibitor (NecroX-7; NecX) against myocardial ischemia-reperfusion injury using in vitro and in vivo models. H9C2 rat cardiomyoblasts and neonatal cardiomyocytes were exposed to hypoxia-reoxygenation stress after pre-treatment with NecX, vitamin C, a combination of vitamin C and E, N-acetylcysteine, an apoptosis inhibitor (Z-VAD-fmk), or cyclosporine A. The main mechanism of cell death after hypoxia-reoxygenation stress was not apoptosis but necrosis, which was prevented by NecX. Protective effect of NecX was based on its potent reactive oxygen species scavenging activity, especially on mitochondrial reactive oxygen species. NecX preserved mitochondrial membrane potential through prevention of Ca2 influx and inhibition of mitochondrial permeability transition pore opening, which was more potent than that by cyclosporine A. Using Sprague-Dawley rats exposed to myocardial ischemia for 45 minutes followed by reperfusion, we compared therapeutic efficacies of NecX with cyclosporine A, vitamin C, a combination of vitamin C and E, and 5% dextrose, each administered 5 minutes before reperfusion. NecX markedly inhibited myocardial necrosis and reduced fibrotic area to a greater extent than did cyclosporine A and other treated groups. In addition, NecX preserved systolic function and prevented pathological dilatory remodeling of left ventricle. The novel necrosis inhibitor has a significant protective effect against myocardial ischemia-reperfusion injury through inhibition of mitochondrial permeability transition pore opening, indicating that it is a promising candidate for cardioprotective adjunctive measure on top of reperfusion therapy.

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