Glucose and Insulin Supplementary Solution Successfully Extended Cardiac Preservation at Subzero Nonfreezing Supercooling Storage in Rat Heart Transplant

Prolonged cold storage can lead to significant ischemic damage in the heart. The glucose–insulin–potassium (GIK) solution exhibits potential antioxidant properties in the context of cardiac ischemia. However, the effects of GIK on hearts subjected to extended cold preservation conditions remain largely unexplored. Therefore, this study aimed to evaluate the protective role of GIK against cold‐induced ischemia–reperfusion injury using a rat heart transplantation model. Rat hearts were preserved at either 4°C or −8°C in a multiple‐saccharide (MS) solution, with or without GIK supplementation, for extended durations (8, 16, or 24 h). Myocardial enzyme levels, markers of oxidative damage, and indices of myocardial apoptosis were quantified both before and after transplantation. Compared with hearts stored in MS solution at 4°C for 8 h, those preserved in GIK‐supplemented solution exhibited significantly higher myocardial ATP content, markedly lower serum myocardial enzyme levels, enhanced glutathione activity in cardiac tissue, and reduced malondialdehyde concentration (all p < 0.05). Moreover, the GIK supplementary solution enabled stable nonfreezing preservation of the heart at −8°C. Notably, the rebeating time and rate of hearts preserved with the GIK‐supplemented solution at −8°C for 16 h—and even up to 24 h—were comparable to those of the standard MS solution at 4°C for 8 h. In summary, GIK supplementation provides cardioprotection against cold‐induced injury by reducing oxidative stress and enhancing antifreezing effects. Consequently, the GIK supplementary solution effectively prolongs the viable preservation time of cardiac tissue during supercooling preservation.