Protective effects of isoflurane delayed preconditioning on rabbit myocardium after ischemic-reperfusion

Objective To investigate the protective effects of isoflurane delayed preconditioning on myocardial ischemia reperfusion injury in rabbit myocardium.Methods Thirty New Zealand male white rabbits were randomly assigned to 3 groups:control group,1.0%isoflurane group and 2.0% isoflurane group.Group 2 and group 3 were respectly exposed to 1.0% isoflurane-100% oxygen and 2.0% isoflurane-100% oxygen for 2 h.Group 1 exposed 2 h to 100% oxygen served as untreated controls.Twenty-four hours laterall rabbits underwent 40 min of coronary occlusion followed by 2 h of reperfusion.Blood samples were taken from arterial line at 20 min before occlusion(T1),20 min after occlusion(T2),40 min after occlusion(T3),1 h after reperfusion(T4) and 2 h after reperfusion(T5) for determination of plasma cTnI levels.At the end of the reperfusion,infarct size(IS) and area at risk(AAR) were defined by Evans and TTC staining.Results The cTnI levels of group 2 and group 3 were significantly lower than that of group 1(P0.05).Isoflurane significantly(P0.05)reduced infarct size(24.2%±2.1%) in group 2,(19.7%±2.8%) in group 3 of the left ventricular area at riskas compared with control(37.8%±1.7%) in group 1.The injury of group 1 was worse than that of group 2 and group 3 from the changes of the cellular structure under light microscope.Group 2 and group 3 had a lower levels of MDA and also had a higher level of SOD.Conclusison Isoflurane preconditioning induces late cardioprotection against postischemic reperfusion injury in rabbits.