Study on the effect of diazoxide postconditioning combined with diazoxide preconditioning on myocardial ischemia/reperfusion injury

Objective: To investigate the effect of diazoxide postconditioning combined with diazoxide preconditioning on myocardial ischemia/reperfusion injury in isolated rat heart.Methods: Isolated working heart models of Wistar rats were set up.Forty-eight wistar rats were divided randomly into 6 groups: the Con group in which the left anterior descending artery(LAD) was ligated for 45 mins and followed by 120 mins perfusion;the Pos group in which 6 cycles of 10-seconds-reperfusion and 10-second-occlusion were carried out on the aortic perfusion tube before the full restoration of blood flow;the Dpo group in which the hearts were reperfused with solution containing diazoxide(50 μmol/L) during the reperfusion;the Dpr group in which solution containing diazoxide(50 μmol/L) was perfused before the ligation of LAD;the Cbm group in which solution containing diazoxide(50 μmol/L) was perfused both before and after the ligation of LAD;the Dhb group in which solution containing diazoxide(50 μmol/L) and 5-hydroxydecanoate(5HD,100 μmol/L) was perfused both before and after the ligation of LAD.Results: Compared with Con group and Dhb group,the Flameng score,the pressure-heart rate production,the maximum change rate of left ventricular pressure rise and fall(±dp/dtmax) and coronary flow increased,LDH leakage decreased and the content of SOD was higher,while the content of CK and the content of MDA were lower in Pos group,Dpo group,Dpr group and Cbm group.No additive effect was shown in Cbm group.Conclusion: Diazoxide postconditioning combined with diazoxide preconditioning has cardioprotective effect on myocardial ischemia/reperfusion injury in isolated rat heart,and it shows no additive effect.