Pinacidil-postconditioning is equivalent to ischemic postconditioning in defeating cardiac ischemia-reperfusion injury in rat

Ischemic postconditioning (IPO) had been reported as a promising method against myocardial ischemia-reperfusion (I/R) injury, but IPO was later proved with poor clinical benefit. In this study, we compared the protective effects of pinacidil-postconditioning (PPO) and IPO against myocardial I/R injury. Langendorff rat hearts were randomly assigned to one of the following groups (n=8 each): Control group, I/R group (40 min ischemia and 60 min reperfusion), IPO group (6 successive cycles of 10 s reperfusion per 10 s occlusion before fully reperfusion), PPO group (perfused with 50 μM pinacidil for 5 min before reperfusion). Heart performance, infarct size and mitochondrial respiratory function were evaluated, and target genes/proteins of well-known Nuclear Factor-E2 Related Factor 2 (Nrf2) were assessed. Both IPO and PPO preserved heart function and myocardial ultrastructure at the end of reperfusion (all P<0.05 vs. I/R). The expression of Nrf2, NADH-quinone oxidoreductase-1 (NQO1), heme oxygenase 1 (HO-1) and superoxide dismutase 1 (SOD1) were similarly increased after IPO and PPO treatment (all P<0.05 vs. I/R). PPO exerted solid effect in defeating cardiac ischemia-reperfusion injury in rat.