| The burden of myocardial ischemia/reperfusion (IR) injury is 2–3-folds higher in diabetic patients, so protecting
diabetic hearts is clinically important. Here, we investigated the effect of combinational therapy with vildagliptin
and ischemic postconditioning (IPostC) on cardioprotection and the expression of genes regulating autophagy and
mitochondrial function in diabetic hearts with IR injury. Type 2 diabetes was induced through high-fat diet and
streptozotocin protocol in Wistar rats. Vildagliptin was orally administered to diabetic rats 5 weeks before IR injury.
Myocardial-IR injury was modeled by ligation of left the coronary artery for 30 min followed by 60-min reperfusion,
on a Langendorff-perfusion system. IPostC was applied at early reperfusion as 6 alternative cycles of 10-s reperfusion/
ischemia. Creatine-kinase levels were measured spectrometrically, and infarct size was evaluated by TTC staining
method. Left ventricles were harvested for assessing the expression levels of autophagy and mitochondrial-related
genes using real-time PCR. Induction of diabetes significantly increased creatine-kinase release in comparison to
healthy rats, and all treatments significantly reduced the release of enzyme toward control levels (P < 0.05). Only
the combination therapy (IPostC + vildagliptin) could significantly reduce the infarct size of diabetic hearts as
compared to untreated diabetic-IR group (P < 0.01). The levels of autophagy genes LC3 and p62 were significantly
higher in diabetic groups than healthy ones. Induction of IR injury in diabetic hearts enhanced mitochondrial fission
(drp-1) and reduced mitochondrial fusion (mfn1 and mfn2) genes. IPostC alone had no significant effect on the gene
expression and vildagliptin alone could only affect LC3-II and mfn2 expressions. Nevertheless, administration of
combination therapy significantly reduced the expression of both autophagy genes and increased both LC3-II/I and
mfn2/1 ratios as compared with diabetic-IR hearts (P < 0.01–0.05). Application of this combination therapy could
overcome the diabetes-induced failure of cardioprotection by individual treatments and improve mitochondrial dynamic
and autophagy flux |