Effects of methylene blue pretreatment on protection of hepatic ischemia-reperfusion-induced lung injury in rats

Objective To explore the mechanism of hepatic ischemia-reperfusion-induced lung injury and the protection of methylene blue. Methods Thirty-six SD rats were randomly divided into sham operation group(S group,n=12),ischemia/reperfusion group(I/R group,n=12) and methylene blue group(MB group,n=12).Total hepatic I/R was produced by occlusion of hepatic helium for 30 minutes,and the occlusion was then released for reperfusion.In I/R group and MB group,methylene blue(10mg/kg) or normal saline of the same volume was administered intraperitoneally 10 min before ischemia,the animals were killed at 1h of reperfusion.In sham-operation group,the hepatic helium was not occluded,normal saline was injected and the animals were killed at corresponding time.Then the lung tissue was taken for determination of W/D ratio,MDA content,SOD activity,MPO activity,and histological examination,and the levels of serum TNF-α and IL-8 were measured.Results Histological examination revealed that hepatic ischemia-reperfusion-induced lung injury was alleviated in MB group than that in I/R group.The W/D ratio,MDA content,SOD activity,MPO activity,and the levels of serum TNF-α and IL-8 were higher in I/R group than those in S group(P0.01).And the W/D ratio and levels of serum TNF-α and IL-8(P0.01) and MDA content,MPO activity(P0.05) were lower in MB group than those in I/R group.Conclusion Methylene blue pretreatment can protect the lung from injury induced by hepatic ischemia-reperfusion in rats.