Effects of hypoxia on intestinal permeability and small intestinal histopathology in rats exposed to high altitude

Objective To observe the histological and ultrastructural changes of intestinal mucosa in rats exposed to high altitude and to evaluate the intestinal permeability by two-sugar absorption test with a specific high performance liquid chromatography(HPLC).Methods Rats were exposed to 5 500 m high altitude in a hypobaric chamber.After 3 weeks,the morphological changes of intestinal mucosa were observed under light and transmission electron microscopy(TEM).Urine samples were collected by HPLC.The excretion rate of mannite to the excretion rate of lactulose(L/M) was calculated.Results After exposed to high attitude of hypoxia,the intestinal endothelial cells showed a series of pathological injuries,including mucosal thinning,hydropsia and villus shortening.TEM observation indicated a shorter,lodging,partial absence of microvilli on the surface of absorptive cell and mitochondria swelling,mitochondrial cristae sparse or disappear.The apoptosis of intestinal mucosal cells was also commonly observed.The enteric permeability in hypoxia group was higher than that in control group(P0.01).Conclusion Exposure to high altitude can influence mucosa structure of small intestine,increase the intestinal permeability and damage the intestinal mucosal barrier.