Objective To study the effects of Lipoxins A4(LXA4)on the expressions of aquaporin(AQP)1,3,5 in type Ⅱ pneumonocytes(ATⅡ)of rat treated with lipopolysaccharide(LPS).Method One pathogenfree male Spree Dawley(SD)rat every time.weighing 200～250 g,were used for the study.The typeⅡpenumonocytes of rats were isolated and purified,and the changes of cellular ultrastructure were observed by electron microscope in order to get the purity quotien＞90%.The type Ⅱ pneumonocytes were divided randomly into five groups,namely,vebicukun group(alcohol 0.7μL/mL),control group,LXA4 group(1×10-7mol/mL),endotoxin group(LPS 1μg/mL)and LXA4+LPS group(LXA4 1×10-7mol/mL,LPS 1μg/mL).AQP-1,3,5 mRNA of in the typeⅡpenumonocytes were assayed by using reversal transcription poly chain reaction(RT-PCR),and the expressions of AQP-1,3,5 protein were detected by using.immunohistochemistry(IHC).One each specimen,these tests were repeated for six times.ANOVA was used for statistical analysis.Results RT-PCR and IHC showed that when AT Ⅱ treated with 1 μg/mL LPS for 4 hours,the AQP-1,3,5 mRNA and the expressions of AQP-1,3,5 protein were significantly decreased in LPS group compared with control group(P＜0.01).However,the AQP-1,3,5 mRNA and the expressions of AQP-1,3,5 protein after application of LXA4 significandy increased in LPS+LXA4 group in comparison with LPS group(LPS+LXA4,AQP1:0.647±0.132,AQP3:0.900±0.856,AQP5:0.879±0.058;LPS,AQP1:0.297±0.133,AQP3:0.512±0.113,AQP5:0.647±0.110;P＜0.01).The AQP-1,3,5 mRNA and the expressions of AQP-1,3,5 protein were aignificandy increased in LXA4 group in comparison with control group(LXA4,AQP1:0.539±0.142,AQP3:0.818 4-0.176,AQP5:0.841±0.066;Blank Control,AQP1:0.518±0.139;AQP3:0.138±0.136,AQP5:0.766±0.066;P＜0.01).Conclusions AQP-1,3,5 exist in typeⅡpenumonoeyte of rata,and the LXA4 can up-regulate the mRNA and protein expressions of AQP-1,3,5 in Type Ⅱ penumonocytes of rats treated with LPS.