Ischemic Postconditioning And Heptanol Postconditioning Attenuate Myocardial Ischemia-Reperfusion Injury Of Heart Isolated In Rats

Background and objective:The concept of ischemic postconditioning was first introduced in 2003 by Zhao et al.Since it specifically aims at dealing with ischemia after it occurs,thus it possesses more credits in the perspective of clinical application comparing to ischemic preconditioning.In recent years, many researches indicated that gap junction communication mediates the cardioprotective effect against ischemia-reperfusion injury.Heptanol is a kind of fat soluble gap junction uncoupler which can reversibly inhibit the opening of gap junction.Based on what stated above,the objective of this research is to investigate the improvement of myocardial ischemia-reperfusion injury by ischemic postconditioning and heptanol postconditioning of heart isolated in rats.Methodologies:64 health Sprague-Dwaley rats were randomly divided into 2 main groups(n=32).Each main group was then devided into 4 sub-groups (n=8),normal control group(NC),ischemia-reperfusion group(IR),ischemic postconditioning group(IPO) and heptanol postconditioning group(HP). Langendorff apparatus were introduced to set up a langendorff-perfusion heart model isolated in rats.After stablisation,connected it with MPA-cardiac function acquistion and analytical system.To observe the impact of IPO and HP on cardiac hemodynamics after ischemia reperfusion,determin coronary flow flux,creatine kinase isoenzyme MB(CK-MB).meanwhile,to observe the impact on myocardial tissues after ischemia reperfusion.To monitor the electrocardiogram with the MS4000U bio-signal analytical system,The arrhythmia scores and the left ventricular fibrillation thresholds were used to evaluate the impact of IPO and HP on ischemia reperfusion arrhythmia.Results:â‘ Comparing to the IR group,the IPO group showed the more improvement of left ventricular function,and better recovery of heart rate (HR)and cononary flow(CF),and CK-MB decreased significantly after ischemia reperfusion.Also there were in weakening the damage of myocardial cells significantly in the IPO group.Whereas comparing to the IR group,the HP group had significant impact on reducing the level of the damage on myocardial cells and decreasing the quantity contained of creatine kinase isoenzyme MB (CK-MB),it didn't have significant impact on ischemic cardiac systolic and diastolic function and coronary flow.Meanwhile it restrained the heart rate of a ischemic heart.â‘¡Comparing to the IR group,both IPO and HP groups could more significantly improve the ventricular fibrillation threshold and decrease the ventricular arrhythmia.Conclusion:In the isolated rat hearts,ischemic postconditioning could protect the myocardium cells after ischemia reperfusion.It also could improve the left ventricular function and reduce reperfused arrhythmia.Similar to IPO group,the Hepanol postconditioning could weaken the damage of myocardial cells and reduce reperfused arrhythmia after ischemia reperfusion.