| Objective:To investigate the effects of different concentration of sevoflurane on rat's myocardial ischemia/reperfusion injury.Methods:thirty-two aged wistar's rats(body weight mean 250-300g)were anaesthetized with chloralhydrate 0.3mgkg-1 intramuscularly.Self-made tracheal tube was intubated throught the tracheostomy. the rat's lungs were ventialated with a tidal volume of 5 ml/kg at 60 beats per minutes. The rats were instrumented for measurement of mean aterial pressure(MAP,catheter in the left femoral artery),heart rate(HR).A ligature snare was looped around a major coronary artery for later occlusion.All rats underwent coronary anatomy of rats is highly variable and does not follow the classical scheme with only two main branches of the left coronary artery.The major branch of the left coronary artery serving the left anterior wall was used for ischemia and reperfusion.Hemodynamic variables were recorded after a 10-min stabilization period.Regional myocardial ischemia was induced by tightening the snare around the prepared coronary artery. Myocardial ischemia was verified by the appearance of epicardial cyanosis.At the beginning of ischemia,the rats received sevoflurane in an end-tidal concentration of 1vol%(1%sev group n=8),2vol%(2%sev group n=8,1 MAC in rats),3vol% (3%sev group n=8)for 10 min.By using a high inspiratory flow of 5 L·min-1,stable sevoflurane concentrations could be achieved within 1 min as evidenced by rapid changes in hemodynamics already during the first seconds of sevoflurane administration.Sevoflurane concentration was measured in the expiratory gas(Datex Capnomac Ultima,Division of Instrumentarium Corp.,Helsinki,Finland)at a sampling rate of 200 mL·min-1.Control rats(n=8)did not receive sevoflurane during ischemia.Then,all the hearts were subjected to local ischemia,hearts were reperfused for 30 min,MAP and HR were recorded before ischemia,at 10min, 30min,1h after reperfusion.CK and LDH were measured before ischemia and at 2h of reperfusion.Significant differences were observerd among four groups.After 2'h reperfusion,some tissue of heart were stained by HE dyeing method to observe the infarct region;the others we used TTC staining after 2 hours of reperfusion to determine infarct size(Infract size were calculated by software named Scion Image programe).Result:(1)The results of hematoxylin eosin(HE)dyeing demonstrated that the model of acute myocardial infarction in mouse is builded successfully.The pathology pictures showed that compared with I/R group,the degree of myocardial infarction in preconditioning groups relieved significantly(Figure1,2,3,4,5,6,7,8,9);(2)There are no significant differences of HR,MAP,CK,LDH among four groups before ischemia(P＞0.05);(3)The HR,MAP in each group tend to decrease after ischemia, but there are no significant differences between them(P＞0.05);in each group,there are significant differences of HR,MAP at differences time(P＜0.05),showing that the heart function before ischemia is much better than after reperfusion.(4)In each group,there are significant differences of CK,LDH between before ischemia and the end of reperfusion(P＜0.05).There are significant differences of CK,LDH between I/R group and preconditioning groups(1%sev,2%sev,3%sev groups)at the end of reperfusion(P＜0.05).Among preconditioning groups,there are no significant differences of CK and LDH at the end of reperfusion(P＞0.05).(5)It is obviously to distinguish the infraction myocardium and no infraction myocardium among four groups by TTC dyeing(figure 13,14,15,16,17).There are significant differences of infraction region between I/R group and preconditioning groups(1%sev,2%sev,3%sev groups)(P＜0.05),no significant differences of infraction size can be founded between 1%sev group and 3%sev group,but there are significant differences of infraction size between 2%sev,3%sev group and 1%sev groups(P＜0.05).Conclusion:1.There are significant differences infraction region in four groups.2.Precondition of sevoflurane have effectively protects the heart against ischemia/ reperfusion injury in rats in vivo.3.2%and 3%sevoflurane can provide maximal protection against reperfusion injury in the rat heart in vivo.The effects of cardioprotection is no significant differences between their.
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