Abstract:

Abstract:Objective
To study the influence of 17β-estradiol and progestogen in type Ⅱalveolar epithelial Na+ channel（ENaC）in rats with acute lung injury(ALI) and explore the mechanism of estradiol and progestogen in  promoting the  clearance of alveolar fluid.Methods 40 immature female SD rats were randomly assigned into 4 groups: normal control group(injected with 8 mL?kg-1 saline via venous),ALI model group,17β-estradiol and  progestogen  combination A and B group.The rats in last three group were injected with 0.1  mL?kg-1 oleic acid via venous to establish ALI model.The rats in combination A and B groups  were injected subcutaneously with 17β-estradiol and  progestogen mixed liquor 0.1 mL in different ratios (A group 1∶1　000，B group 1∶200) at 12 and 36 h before oleic acid injection.All the rats were sacrificed at 6 h after oleic acid injection.The wet/dry ratio and the lung coefficient were determined, the pathological changes of  lung  tissues  were  observed, and the expressions of α-ENaC,β-ENaC and γ-ENaC mRNA and protein were determined.Results
① Compared with normal control groups,the wet/dry ratio and the lung coefficient in ALI model group were increased significantly (P<0.01);in combination A and B groups, the wet/dry ratios and the lung coefficients were decreased compared with model group，especially in  A group (P<0.05).②Obvious pulmonary edema,bleeding and inflammatory cell infiltration were observed in ALI group.However, the extent of  pulmonary edema,bleeding and inflammatory cell infiltration were decreased markedly in combination  A and B groups, especially in  A groups.③ Compared with normal control group,the  expressions of α-ENaC and γ-ENaC mRNA and protein were decreased in ALI model group(P<0.01); compared with ALI group,they were increased significantly in combination A and B groups,especially in A  group(P<0.05).Conclusion 17β-estradiol and progestogen can increase the expressions of  type Ⅱ alveolar epithelial α-ENaC and γ-ENaC mRNA and protein in rats with ALI,and promote the clearance of alveolar fluid.

Key words: estrogen； progestogen；sodium channel；acute lung injury；acute respiratory distress syndrome