Effect Of Ischemic Postconditioning And Pharmacological-conditioning Induced By ATP After Acute Ischemic Injury

Objective To evaluate the cardioprotective effects offered by the postconditioning and pharmacological-conditioning induced by ATP comparing with the preconditioning and discuss postconditioning' mechanism. Method In anesthetized open-chest rabbits, the left anterior descending artery (LAD)was occluded for 40 mins and reperfused for 3 hours. In controls(n=8), there was no intervention. In Pre-con(n=8), the LAD was occluded for 5 min and reperfused for 10 min before the prolonged occlusion. In Post-con(n=8),at the start of reperfusion, three cycles of 30-s reperfusion and 30-s LAD reocclusion preceded the 3 hours of reperfusion. In ATP group(n=8), at the start of reperfusion, ATP is injected as a velocity of 300ug/kg/min continued 30rains. Results Infarct size was significantly less in the Pre-con(P<0.001), Post-con(P<0.01) groups and ATP(P<0.05) compared with controls. The levels of CPK in the Pre-con , Post-con and ATP groups were significantly less than controls on the three points. SOD, a antioxidant ,was significantly higher at 3 hour of reperfusion in Post -con versus controls(P<0.05) associated with a decrease in MDA levels versus controls(P<0.05). Conclusion These data suggest that Post-con is as effective as Pre-con in reducing infarct size and CPK of serum. Post-con is partly due to reducing the injury of oxygen free radical. When used as reperfusion, ATP is effective and ATP may become a promising agent.