Structural and Alveolar Fluid Clearance Changes in Hypoxic Rat Lungs

Objective To study the ultrastructural and alveolar fluid clearance(AFC) changes in hypoxic rat lungs,and to investigate the relationship between them.Methods One hundred and twenty male Wistar rats weighing 300-380 g were randomly divided into twelve groups.The hypoxic rats were generated by exposure to 10% oxygen.Basal AFC and total lung water(TLW) stimulated by terbutaline were measured at 24 h,48 h and 72 h,respectively.The specimens were examined by electron microscopy.Results After the rats were exposed to 10% oxygen concentration for 24 h,the level of AFC(18.7±3.19%) showed no marked difference compared with that of normal rats(18.9±2.26%).The capillary endothelial cells had some injury changes while the alveolar epithelial cell showed no remarkable change.At 48 h,AFC(13.6±2.60%) decreased markedly while the alveolar epithelial cells had no obvious structural change.At 72 h,the level of AFC(9.93±1.95%) decreased further,and the AFC stimulated by terbutaline showed marked difference with that of normal rats.The alveolar epithelial cells presented marked changes.Conclusion In the setting of mild and moderate lung injury,although AFC is deceased,the structure of alveolar epithelial barrier may not necessarily be markedly changed,and the response to drug effects upon AFC can still be well maintained.