The Research Of The Protection Of Isoflurane Delayed Preconditioning To Myocardial Ischemia Reperfusion Injury In Rabbit

Part one the protection of Isoflurane delayed preconditioning on rabbit myocardium after ischemic reperfusion.Objective To investigate the protection of Isoflurane delayed preconditioning on myocardial ischemia reperfusion injury in rabbit. Methods Fourty New Zealand male white rabbits were randomly assigned to 4 groups:(1)sham group;(2)I/R group;(3)1.0%isoflurane group;(4)2.0%isoflurane group.Group 3 and group 4 were respectly exposed to 1.0%isoflurane-100%oxygen or 2.0%isoflurane-100% oxygen for 2 h.Group 2 exposed 2 h to 100%oxygen served as untreated controls.Twenty-four hours later Group 2-4 underwent 40 min of coronary occlusion followed by 120 min of reperfusion.Blood samples were taken from arterial line at 20min before occlusion(T1),20min after occlusion(T2),40min after occlusion(T3),60min after reperfusion(T4) and 120min after reperfusion(T5)for determination of plasma cTnI,LDH and CK 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,LDH and CK levels of group 3 and group 4 were significantly lower than that of group 2(P＜0.05).Isoflurane delayed preconditioning significantly(P＜0.05)reduced infarct size(24.2%±2.1%in group 3, 19.7%±2.8%in group 4)compared with control(37.8%±1.7%in group 2).The injury of group 2 was worse than that of group 3 and group 4 from the changes of the cellular structure under light microscope.Group 3 and group 4 had a lower levels of MDA and also had a higher level of SOD than group 2.Conclusion Isoflurane preconditioning induces late cardioprotection against ischemia reperfusion injury in rabbits.Part two the signal mechanism of Isoflurane delayed preconditioning on myocardium during ischemia-reperfusion in rabbitObjective:To investigate the signal mechanism of Isoflurane delayed preconditioning on myocardium during ischemia-reperfusion in rabbit.Methods:Fourty New Zealand male white rabbits were randomly assigned to 5 groups:(1)sham group;(2)I/R group;(3)2.0%Isoflurane group;(4)SB203580+2.0%Isoflurane group,(5)naloxone+2.0% Isoflurane group.Group 3,group 4 and group5 were exposed to 2.0% isoflurane-100%oxygen for 2h.Administration of SB203580,a special p38MAPK inhibitor(2mg/kg)in group 4,or naloxone,an opioid inhibitor(6mg/kg)in group 5,15 min before isoflurane treatment.Group 1 and group 2 were exposed 2 h to 100%oxygen served as untreated controls.Twenty-four hours later,all groups except group 1 underwent 40 min of coronary occlusion followed by 2 h of reperfusion.At the end of the reperfusion,infarct size(IS)and area at risk(AAR)were defined by Evans and TTC staining.The heart was harvested and the levels of p38MAPK,NF-κB,Bcl-2 and Caspase-3 activity were determined by Western Blot analysis.Results:The activity of p38MAPK,NF-κB and Caspase-3 in group 3 and group 4 were significantly lower than that of group 2(P＜0.05).The activity of Bcl-2 in group 3 and group 4 were significantly higher than that of group 2(P＜0.05).The activity of p38MAPK,NF-κB,Bcl-2 and Caspase-3 in group 5 was the same high as that of group 2(P＞0.05).Isoflurane significantly(P＜0.05)reduced infarct size(19.7%±2.8%in group 3)as compared with control(37.8%±1.7%in group 2).Administration of naloxone abolished the delayed cardioprotective effects of isoflurane,except SB203580.Conclusion: Isoflurane can inhibit the activity of p38MAPK,NF-κB and Caspase-3 and promote the activity of Bcl-2 in myocardium during ischemia reperfusion,which maybe one of molecular mechanisms of Isoflurane delayed preconditioning on cardioprotection and maybe mediate by opioid receptor. Part three proteomic analysis of Isoflurane delayed preconditioning on rabbit myocardiumObjective To search for global protein changes of isoflurane delayed preconditioning on rabbit myocardium by using proteomic technology.Methods Eight New Zealand white rabbits of both sexes were randomly assigned to group I/R and group S.Both groups underwent ligation of the left anterior descending coronaryartery(LAD) for 40 minutes and reperfusion for 120 minutes.Group S received 2.0% isoflurane for 120 min that was discontinued 24 h before ischemia and reperfusion.Results Differential analysis using the Student's t-test(P＜0.05)showed that the expression of 13 protein spots changed,11 protein spots were identified by mass spectrometry.Conclusions Isoflurane delayed preconditioning resulted in the changes of protein expression profiles in the myocardium.The differential proteins might function as molecular chaperone,decrease free radical and promote the energy metabolism of myocardium to confer cardioprotection. Part four the mechanism of heat shock protein mediate the protection of Isoflurane delayed preconditioning on myocardium during ischemia reperfusion in rabbitObjective:To investigate the mechanism of Heat Shock protein mediate the protection of Isoflurane delayed preconditioning on myocardium during ischemia-reperfusion in rabbit.Methods:Fourty New Zealand male white rabbits were randomly assigned to 5 groups: (1)sham group;(2)I/R group;(3)2.0%Isoflurane group;(4)SB203580+2.0 %Isoflurane group;(5)naloxone+2.0%Isoflurane group.Group 3,group 4 and group5 were exposed to 2.0%isoflurane-100%oxygen for 2 h. Administration of SB203580,a special p38MAPK inhibitor(2mg/kg)in group 4,or naloxone,an opioid inhibitor(6mg/kg)in group 5,15 min before isoflurane treatment.Group 1 and group 2 were exposed 2 h to 100%oxygen served as untreated controls.Twenty-four hours later,all groups except group 1 underwent 40 min of coronary occlusion followed by 2 h of reperfusion.At the end of the reperfusion,infarct size(IS)and area at risk(AAR)were defined by Evans and TTC staining.The heart was harvested and the levels ofaB-Crystallin and HSP27 activity were determined by Western Blot analysis.Results:The activity ofaB-Crystallin and HSP27 in group 3 and group 4 were significantly higher than that of group 2(P＜0.05).The activity ofaB-Crystallin and HSP27 in group 5 was the same high as that of group 2(P＞0.05). Isoflurane significantly(P＜0.05)reduced infarct size(19.7%±2.8%in group 3)as compared with control(37.8%±1.7%in group 2). Administration of naloxone abolished the delayed cardioprotective effects of isoflurane,except SB203580.Conclusion:Isoflurane can promote the activity ofaB-Crystallin and HSP27 in myocardium during ischemia reperfusion,which maybe one of molecular mechanisms of Isoflurane delayed preconditioning on cardioprotection.