The Study Of Postconditioning On Myocardial Ischemia/reperfusion Injury In Rabbits

Objective: We tested the hypothesis that repetitive ischemia applied during early reperfusion, i.e., postconditioning, is cardio-protective by attenuating reperfusion injury.Methods: In anesthetized open-chest rabbits, the left anterior descending artery (LAD) was occluded for 30 min and reperfused for 3 h, all rabbits were randomly divided into four groups, In controls (n = 5), there was no intervention. In Pre-groups (n = 5), two circles of 5-min coronary occlusion and 5-min reperfusion before the prolonged occlusion. In Post- groups(n =5), at the start of reperfusion, five cycles of 30-s reperfusion and 30-s LAD reocclusion preceded the 3 h of reperfusion. In Pre- plus Post- groups (n = 5), two circles of 5-min coronary occlusion and 5-min reperfusion before the prolonged occlusion, then five cycles of 30-s reperfusion and 30-s LAD reocclusion preceded the 3 h of reperfusion.. Results: Infarct size was significantly less in the Pre-,Post- and Pre- plus Post- groups compared with controls (14.71±6.03 14.68±5.60 13. 89±7. 04 versus 26. 67±6.66%) (p<0. 05) , consistent with a reduction in plasma creative kinase activity (CK-MB 5055±728 5422±1190 5545±1032 versus 6903 + 1315 U/L) and lactate dehydrogenase (LDH 299±50 369 + 23 316±59versus 528±99 U/L) in these groups; infarct size was not further reduced by Pre- plus Post-; Plasma malondialdehyde , a product of lipid peroxidation, was significantly less at 30rain of reperfusion in Post-,Post- and Pre- plus Post- groups versus controls (MDA3.56±1.95 3.44±1.25 3.08±1.44与4.30±1.52 nmol/ml). These data suggest that Post- is as effective as Pre-in reducing infarct size. Post- may be clinically applicable in coronary interventions, coronary artery bypass surgery, organ transplantation, and peripheral revascularization where reperfusion injury is expressed. Conclusions: it is a good method for making a model of AMI to occlude left coronary anterior descending ; Post- at onset of Reperfusion reduces myocardial injury; cardioprotection may be mediated, in part, by inhibiting oxidant generation and oxidant mediated injury; No additive cardioprotective effects by Pre- plus Post- were observed in a rabbit model of regional ischemia and reperfusion.