CORM-3 mitigates hypoxia/reoxygenation-induced injury in neonatal rat cardiomyocytes by regulating Mitochondrial-Mediated apoptosis and complex IV activity.

Background: Myocardial ischemia-reperfusion injury (MIRI) is a major contributor to myocardial infarction and leads to significant myocardial dysfunction. Mitochondria, crucial for cellular energy production, are particularly susceptible to damage during ischemia/reperfusion (I/R) events. Carbon monoxide-releasing molecule-3 (CORM-3), a water-soluble compound that releases carbon monoxide (CO), has demonstrated multiple protective effects against I/R injury. Mitochondria are recognized as selective targets for CO's protective actions in cells.

Purpose: This study aimed to explore whether CORM-3 mitigates cardiomyocyte injury during hypoxia/reoxygenation (H/R) by regulating the mitochondrial-mediated apoptosis pathway and mitochondrial respiration.

Methods: Neonatal rat cardiomyocytes were cultured and randomly assigned into four groups: control group, H/R group (hypoxia for three hours followed by reoxygenation for six hours), CORM-3 group, and inactivated CORM-3 (iCORM-3) group. CORM-3 and iCORM-3 (12.5 µmol/L) were administered at the onset of hypoxia. Mitochondrial ultrastructure was assessed using transmission electron microscopy. The protein levels of caspase-3, caspase-9, mitochondrial cytochrome c, and cytosolic cytochrome c were analyzed via western blot. Mitochondrial membrane potential and intracellular reactive oxygen species (ROS) were measured by flow cytometry. ATP levels were quantified using an ATP Assay Kit, and mitochondrial respiratory chain complex IV activity was determined using a cytochrome oxidase activity colorimetric assay kit.

Results: CORM-3 effectively reduced myocardial mitochondrial structural damage induced by H/R and downregulated the expression of caspase-3, caspase-9, and cytosolic cytochrome c. Moreover, CORM-3 inhibited cytochrome c release from mitochondria and enhanced mitochondrial membrane potential. Additionally, CORM-3 diminished ROS production and increased the activity of mitochondrial respiratory complex IV in cardiomyocytes. CORM-3 also alleviated the decline in ATP levels following H/R. The protective effects were lost when using inactivated CORM-3 (iCORM-3), suggesting that CO is the active mediator.

Conclusion: The results indicate that CORM-3 effectively alleviates myocardial injury during H/R by inhibiting mitochondria-mediated apoptosis and enhancing mitochondrial respiratory function.