Effects of emulsified isoflurane preconditioning on lung ischemia-reperfusion injury in rats

Objective To investigate the effects of emulsified isoflurane preconditioning on lung ischemia-reperfusion(I/R)injury in rats. Methods Thirty-two male Sprague-Dawley rats, weighing 250-320 g, were randomly divided into 4 groups(n=8 each)using a random number table: sham operation group(group S), group I/R, intralipid group(group IL), and emulsified isoflurane preconditioning group(group EI). Lung I/R was produced by clamping the left hilum of lungs for 1 h followed by 2 h of reperfusion in anesthetized rats.In group S, intraperitoneal normal saline 10.5 ml/kg was injected, but the hilum was only exposed 24 h later.In groups I/R, IL and EI, intraperitoneal normal saline 10.5 ml/kg, 30% intralipid 10.5 ml/kg and 8% emulsified isoflurane 10.5 ml/kg were injected intraperitoneally, respectively, and then the model was established 24 h later.At the end of reperfusion, blood samples were collected from the left ventricle for measurement of PaO2, PaCO2, plasma malondialdehyde(MDA)concentration(by ELISA). The rats were then sacrificed, and left lungs were removed immediately for microscopic examination and for determination of myleoperoxidase(MPO)activity(using colorimetric method)in pulmonary specimens.Wet/dry lung weight ratio(W/D ratio)was calculated. Results Compared with group S, W/D ratio, MPO activity, plasma MDA concentration and PaCO2 were significantly increased, and PaO2 was decreased in the other three groups.Compared with group I/R, W/D ratio, MPO activity, plasma MDA concentration and PaCO2 were significantly decreased, and PaO2 was increased in IL and EI groups.W/D ratio, MPO activity, plasma MDA concentration and PaCO2 were significantly lower, and PaO2 was higher in group EI than in group IL.The pathological changes of the lung were significantly attenuated in group EI compared with group I/R. Conclusion Emulsified isoflurane preconditioning can reduce lung I/R injury in rats, and inhibition of pulmonary inflammatory responses and of production of oxygen free radicals are involved in the mechanism. Key words: Isoflurane; Fat emulsions, intravenous; Ischemic preconditioning; Reperfusion injury; Lung