Abstract
BackgroundHigh altitude pulmonary edema (HAPE) affects individuals and is characterized by alveolar flooding with protein-rich edema as a consequence of blood-gas barrier disruption. In this study, we hypothesized that aquaporin 5 (AQP5) which is one kind of water channels may play a role in preservation of alveolar epithelial barrier integrity in high altitude pulmonary edema (HAPE).MethodsTherefore, we established a model in Wildtype mice and AQP5 −/− mice were assingned to normoxic rest (NR), hypoxic rest (HR) and hypoxic exercise (HE) group. Mice were produced by training to walk at treadmill for exercising and chamber pressure was reduced to simulate climbing an altitude of 5000 m for 48 hours. Studies using BAL in HAPE mice to demonstrated that edema is caused leakage of albumin proteins and red cells across the alveolarcapillary barrier in the absence of any evidence of inflammation.ResultsIn this study, the Lung wet/dry weight ratio and broncholalveolar lavage protein concentrations were slightly increased in HE AQP5 −/− mice compared to wildtype mice. And histologic evidence of hemorrhagic pulmonary edema was distinctly shown in HE group. The lung Evan’s blue permeability of HE group was showed slightly increased compare to the wildtype groups, and HR group was showed a medium situation from normal to HAPE development compared with NR and HE group.ConclusionsDeletion of AQP5 slightly increased lung edema and lung injury compared to wildtype mice during HAPE development, which suggested that the AQP5 plays an important role in HAPE formation induced by high altitude simulation.
Highlights
High altitude pulmonary edema (HAPE) affects individuals and is characterized by alveolar flooding with protein-rich edema as a consequence of blood-gas barrier disruption
Hypoxia exposure procedure Nine Aquaporin 5 (AQP5) −/− knockout mice participated in this study and were randomly assigned as the normoxic rest (NR) group, hypoxic rest (HR) group and hypoxic exercise (HE) group
These results suggest that AQP5 may play, at most in part, an important role in alveolar epithelial barrier function in formation of lung edema involve fluid transport for HAPE
Summary
High altitude pulmonary edema (HAPE) affects individuals and is characterized by alveolar flooding with protein-rich edema as a consequence of blood-gas barrier disruption. We hypothesized that aquaporin 5 (AQP5) which is one kind of water channels may play a role in preservation of alveolar epithelial barrier integrity in high altitude pulmonary edema (HAPE). It is believed that high lung water permeability facilitates fluid formation and resolution of pulmonary edema [8]. The epithelium and the epithelium barrier become the new target of the study in the maintenance of alveolar-capillary integrity and normal alveolar function during HAPE development. High pulmonary vascular pressures when expose to hypoxia result in transient breakdown of the integrity of the alveolar-capillary barrier, permitting fluid accumulation [21,22]. We hypothesized that AQP5 may play an important role in alveolar epithelial barrier function in formation of lung edema involve fluid transport for HAPE. We aimed to test whether AQP5 facilitate the integrity of alveolar epithelia barrier and beneficiate for the integrity of alveolar-capillary barrier, using our established mouse model and explored the possible mechanism
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