Abstract： Objective To observe the levels of Ang - 1 and NF-κB in lung tissue and to aseess the severity of ALI induced by phosgene in order to clarify the mechanism of the protective effect of Ang - 1 on phosgene induced ALI.Method Rats were randomly divided into phosgene group and air group.Another rats were randomly (random number) divided into phosgene group,phosgene + PDTC group and air group.Lung tissue was collected to weigh and calculate the wet / dry weight ratio,measure BALF,white blood cell count,total protein and Ang-1 at given time after exposure to phosgene/air and PDTC.The Ang - 1 and NF-κB levels in lung tissue were measured with Western blot and immunohistochemistry.Data were analyzed by using SPSS 16.0 statistical package and comparisons between groups were carried out byusing One-Way ANOVA analysis and LSD -t test,α ＜ 0.05.Results Serum angiopoietin -1 level became lesser within 48 hours after exposure to Phosgene.The severity of ALI became worser with time elapsing.Ccompare with air group,the severity of ALI in phosgene group was worser with time elapsing ( P ＜ 0.05).Compared with phosgene + PDTC group,the serum angiopoietin -1 and arterial oxygen partial pressure in phosgene group were lower ( P ＜ 0.05).The severity of ALI of rats in phosgene group were worser than that in phosgene + PDTC group ( P ＜ 0.05).Serum angiopoietin -1 and partial pressure of oxygen of rats in phosgene group were higher than those in phosgene + PDTC group ( P ＜ 0.05).Immunohistochemistry test showed that the expression of Ang-1 in lung tissue in air group were normal,and Ang-1 in phosgene group were significantly reduced,and Ang-1 in PDTC intervention group was higher than that in phosgene group and lower than that in air group.The above results were confirmed by Western blot test which was consistent with the results of immunohistochemistry test.Similarly,the levels of NF-κB in lung tissue determined by using both Western - blot and immunohistochemistry were consistant,and results of both methods showed that the expression of NF - κB in air group was normal,and it increased in phosgene group,and the expression of NF-κB in phosgene + PDTC group was lower than that in phosgene group.Conclusions The serum level of Ang-1 was decreasing within 48 hours after ALI.Ang-1 was negatively correlated with the sevfity of phosgene induced ALI.Ang-1 likely had an effect on NF-κB signaling pathway,ameliorating the inflammation mediated by cytokines,reducing lung endothelial permeability and in turn lessening the severity of ALI.