Delayed IPC exerts cardioprotective effect through neovascularization in a rodent permanent occlusive coronary rat model

AIM: To investigate whether delayed ischemic preconditioning (IPC) exerts a cardioprotective effect through arteriogenesis in a rodent permanent occlusive coronary rat model. METHODS: Fifty four rats were randomly divided into four groups. In IPC+acute myocardial infarction (AMI) group (n=24), rat left anterior descending coronary arteries were ligated 24 h after IPC. In AMI group (n=24), rat left anterior descending coronary arteries were ligated without IPC. In IPC group (n=3), rats were subjected to IPC procedure and in sham group (n=3), rats were not subjected to either IPC or ligation. At 3, 7, and 14 days, the heart sections of IPC+AMI group and AMI group rats were obtained to detect the capillary density and arteriole density by immunostaining. Heart function and infarct size were measured by Masson’s trichrome staining and echocardiography in 14-day subgroup. At 24 h, the heart sections of IPC group and sham group were obtained to detect the capillary density and VEGF and PDGF-B expression. RESULTS: Neovascularization was seen in rat heart section 24 h after IPC. Compared with sham group, the expression of VEGF, PDGF-B in heart section in rats of IPC group increased significantly (P<0.05). Compared with those in AMI group, capillary density and arteriole density in heart sections in rats of IPC+AMI group increased in 3-, 7- and 14-day subgroups (P<0.05). Infarct size was reduced and heart function improved in 14-day subgroup (P<0.05). CONCLUSION: Delayed IPC reduces infarct size and improves heart function in a permanent occlusive rat model. This may result from increased functional arteriogenesis, whereas increased expression of VEGF, PDGF-B in heart section in rats of IPC group may contribute to proliferative arteriole.