Abstract
The aim of this study is to evaluate the relationship between the increase in the expression of Na+/Ca2+ exchanger(NCX) and the increased vulnerability to ischemia/reperfusion in the remodeled hearts. The coronary artery of male adult rats was ligated. One week later, the hearts were removed and perfused with Krebs-Henseleit buffer(KHB) solution. Control hearts were perfused with KHB solution for 2 hours. Ischemic hearts were first perfused with KHB solution for 30 minutes, and then the perfusion was perfectly terminated and the hearts were immersed in saline for 30 min. The hearts were perfused again with KHB solution for 1 hour. Western blotting revealed that the expression of cardiac NCX in the remodeled hearts was significantly increased as compared with that in the non-remodeled hearts. Both the secondary ischemia-induced increases in the caspase-3 cleavage and the calpain activity were more intensively detected in the remodeled hearts than those in the non-remodeled hearts. These results suggest that the expression of cardiac NCX is increased in association with cardiac remodeling, and that the secondary ischemia might result in the marked increase in the concentration of intracellular Ca2+ via reversed NCX, leading to the increase in apoptotic cardiomyocytes in the remodeled hearts.
