Effect of methylene blueon liver ischemia-reperfusion injury in rabbits

：Objective To investigatethe effect of methylene blue(MB)on liver ischemia-reperfusion (I/R) injury inrabbits.Methods Twenty-four healthy New Zealand white rabbits of both sexes welshins2.0-2.3 kg were randomly divided into 3 groups (n=8 each):group Ⅰ sham operation(group s);group Ⅱ I/R and group Ⅲ methylene blue (group MB).Theanimals were anesthetized with intravenous 2% pentobarbital 30 mg/kg.Liver I/R wasproduced by occlusion of hepatic blood flow for 40 min followed by 60 min repeffusion.Ingroup MB methylene blue 5 mg/kg was injected iv at 20 min before liver ischemia.Femoralartery was carmulated for MAP monitoring and blood sampling.MAP and HR were recordedimmediately before(T1,baseline)and at 20 and 40 min of ischemia (T2,3) and 1,5,30,60min(T4-7)of repedusion.Blood samples were collected at T1,T5,T6 and T7 for measurement ofseruln TNF-α and IL-6concentrations.Plasma AST and ALT activities were measured at T1,T6 and T7.Liver specimenswere obtained at the end of experiment for determination of SOD activity and MDAcontent.Results In group I/R MAP was significantly decreased at T4-7 during reperfusionand HR at T7 as compared with the baseline at T1;while in group MB no significant changein MAP and HR Was observed during ischemia and reperfusion as compared with thebaseline.The gerum TNF-α and IL-6 concentrations and the plasma ALT and AST activities were significantlyincreased during reperfusion as compared with the baseline immediately before ischemia ingroup I/R and MB and were significantly lower in group MB than in group. I/R. The SODactivity was significantly higher while MDA content was significantly lower in group MBthan in group I/R. Microscopic examination showed that liver damage was less severe ingroup MB than in group I/R. Conclusion The administration of MB can maintain hemodynamicstability and attenuate liver I/R injury in rabbits. Key words: Methylene blue; Reperfusion injury; Liver