Primary Study On The Pathogenesis Of HAPE In Rats

High altitude pulmonary edema (HAPE) may result from acute exposure to high altitude in excess of 3 000 m. Bodies that feel cold and fatigue are much more susceptible to HAPE. The pathogenesis of HAPE has not been well elucidated since no successful animal model of HAPE has been set up so far. It is widely accepted that hypoxic pulmonary hypertension and the alveolus-air barrier dysfunction are two main mechanisms. Recent study reported that the active absorption and diffusion function blood vessel endotheliuni and alveolar epithelial cell membrane was damaged in HAPE patients. Since AQP5 in the I type alveolar epithelial cell plays an important role in eliminating inleaked liquid, we hypothesis that AQP5 may be an essential factor involved in the occurrence of HAPE. In this study, we investigated the blood gas, pulmonary dynamics parameters and the expression of AQP5 in rats exposed to hypoxia, cold and exercise, and replicated the HAPE animal model by simulating the hypoxic combined cold and exercise condition of high altitude. Adult male Wistar rats were randomly divided into 5 groups as following: normal group (N), cold group (C), hypoxic group (H), hypoxia-combine-cold group (HC), hypoxia-combine-cold-and- exercise group (HCE). The animals were anesthetized and cardiac catheter was guided to the right ventricle and pulmonary arterial pressure was recorded. After that, the animal was sacrifised and pulmonary tissues were collected for pathological examination and analysis of AQP5 expression with western-blot and immunohistochemical techniques, and the arterial blood was collected for analysis of blood gas parameters. The main results are as following".1. About 70.2% of rats in HCE group exhibited swollen and thicken of pulmonary tissues. The alveolar cavity was smaller in HCE group than any other group, but not a case of alveolar edema was found in each group.2. PaO₂ and SaO₂ was notable lower in the H, HC and HCE groups than that in normal group, but no significant difference was found between C and N groups.3. The pulmonary arterial pressure was significant higher in the H, HC and HCE groups than that in normal group, but no significant difference was found between C and N...