Objective To study the effect of aquaporin 1 on intestinal capillary endothelial barrier in rats with experimental acute necrotizing pancreatitis (ANP).Methods In this study,160 male Sprague-Dawley rats were randomly divided into five groups:Control group ( n =32),ANP group (n =32),NS group,Dexamethasone group,and Acetazolamide group.Eight rats in each group were sacrificed at 3,6,12 and 18 h after induction of experimental models.Volume of ascites and levels of serum amylases were deternined at each time point.Pathological changes in intestine tissues were observed under electron microscope after HE staining.Capillary permeeabilities in intestine tissues were detected by Evans blue (EB) extravasation experiment.The mRNA and protein expressions of AQP1 in intestine tissue were determined by real-time PCR and Western blotting,respectively.Results Serum amylase level in ANP group was significantly higher than that in control group.Amylase level in dexamethasone group was lower than that in ANP group,and amylase level in acetazolamide group was higher than that in ANP group at 12 h (P ＜0.05 ) ; The concentration of EB in intestine tissues at each time point in ANP group was significantly higher than those in control group,and EB in dexamethasone group was lower than those in ANP group at 6,12 and 18 h.EB in acetazolamide group was higher than that in ANP group at 3 h ( P ＜ 0.05 ) ; The mRNA expression of AQPI in ANP group was significantly lower than that in control group.The expression of AQP1 in dexamethasone group was higher than those in ANP group at 6,12 and 18 h,and the expression of AQP1 in acetazolamide group was lower than that in ANP group at 3,6,12 h in intestine tissue ( P ＜ 0.05 ).Protein expression of AQPI in tissues in ANP group was significantly lower than that in control group.The expression of AQP1 in dexamethasone group increased more than that in ANP group at 3,6,12 h,and the expression of AQP1 in acetazolamide group was lower than that in ANP group at 3 h,6 h ( P ＜ 0.05 ).Conclusions The expression of AQP1 is down-regulated in intestine tissue in rats with acute necrotizing pancreatitis,and AQP1 could play an important role in the pathogenesis of capillary endothelial barrier dysfunction.