Abstract
OBJECTIVES: Chronic diabetes impedes cardioprotection in reperfusion injury and hence protecting the diabetic heart would have important outcomes. In this study, we evaluated whether combined postconditioning with ischemia and cyclosporine-A can restore oxidative stress and histopathological changes in reperfusion injury of the diabetic myocardium. MATERIALS AND METHODS: Streptozocin-induced diabetic hearts and nondiabetic controls in eight subgroups (with or without receiving ischemic-postconditioning (IPostC), cyclosporine-A, an inhibitor of mitochondrial permeability transition, or both of them) suffered from 30 min regional ischemia followed by 45 min reperfusion on an isolated-heart Langendorff system. The levels of lactate dehydrogenase (LDH) in the coronary effluent, and the levels of oxidative stress markers including 8-isoprostane, superoxide dismutase (SOD), glutathione peroxidase (GPX), and total antioxidant capacity (TAC) in myocardial supernatant prepared from the ischemic zone were measured using specific kits, spectrophotometrically. Histopathological studies were performed -eosin staining method. RESULTS: Administration of IPostC and cyclosporine-A (alone or together) in nondiabetic hearts potentially reduced the severity of histological changes and level of LDH release as compared with untreated-controls (P<0.05). of any procedures in diabetic hearts did not show significant cardioprotective effects (P>0.1). However, the combined postconditioning with ischemia and CsA exerted significant protective effects in diabetic hearts (P<0.05). CONCLUSION: By augmenting the protective effects of IPostC and CsA through their combined application, reperfusion injury and related oxidative stress are reduced in diabetic hearts similar to non-diabetics.