Protective Mechanism Of Osthole Postconditioning Against Acute Myocardial Ischemia/Reperfusion Injury In Rabbits

【Objective】The present study was designed to investigate the protective mechanism of Osthole postconditioning against acute myocardial injury induced by ischemia/reperfusion in rabbits.【Methods】In anesthetized open-chest rabbits, the left anterior descending artery(LAD) was occluded for 40 mins and reperfused for 120 mins.All rabbits were randomly divided into three groups (n=10 in each group): (1) Myocardial ischemia/reperfusion (I/R) group: LAD occlusion and reperfusion only, with no other intervention; (2) Myocardial ischemic postconditioning (IPTC) group: After 40min of LAD occlusion, reperfusion was initiated for 1min followed by 1min reocclusion, three cycles of myocardial ischemia(1min) and reperfusion(1min) followed the index ischemia/reperfusion protocol;(3) Osthole postconditioning(Ost) group: at the start of reperfusion, Ost(25mg/Kg) was injected within 5mins. levels of serum troponin I(cTnI),creatine kinases(CK) leakage and IL-6 content were tested in right atrial blood which would be extracted at the end of the experiment.Myocardial malondialdehyde(MDA) content,superoxide dismutase(SOD) activity,Ca2+-ATPase activity of mitochondria ([Ca2+-ATPase]m) were tested,and the myocardial ultrastructure injurys were inspected by electriscope.【Results】Levels of serum cTnI,CK leakage and IL-6 content were lower in IPTC and Ost group than that in I/R group respectively(P <0.05,P <0.01), myocardial SOD activity,[Ca2+-ATPase]m activity increased in IPTC and Ost group respectively(P <0.05,P <0.01); myocardial MDA content in IPTC and Ost group were lower than that in I/R group (P <0.05,P <0.01) .levels of serum IL-6 content and [Ca2+-ATPase]m activity were of no statistic significance in IPTC and Ost group respectively(P>0.5).And electron microscopy revealed that the myocardial ultrastructure injurys were less in IPTC and Ost group.【Conclusion】Our data suggest that Osthole postconditioning possesses protective effect for myocardial cell during ischemia/reperfusion.The mechanism of the cardioprotection of osthole injection postconditioning may be associated with raising myocardial activity of SOD, enhance myocardial ability of cleaning oxygen free radidicals, repress over-oxidative reaction of lipid; decreasing the content of MDA, preserve the integrity of cell membrane structure; reducing the release of inflammation medium IL-6,suppress inflammation reaction; increasing myocardial mitochondrial ATP sensitive potassium channel, inhibit calcium overload.