Histochemical and ultrastructural alterations of the duodenum in acute hypoxia.

Laboratory animals were kept for 2, 8 and 16 hours in a pressure chamber, the air of which contained 8% O2 and 92% N2. Histochemical and ultrastructural examinations revealed the following duodenal alterations: 1. The alkaline phosphatase activity of the epithelium and glandular epithelium showed no alteration; the acid phosphatase activity was slightly increased in hypoxia. 2. The succinic dehydrogenase and cytochrome C oxidase activities of the glandular epithelium showed a marked decrease. 3. Two hours of hypoxia led to destruction of the microvillous epithelium. Prolonged hypoxia resulted in the destruction of the microvilli as well as of the cuticula. 4. Hypoxia of short duration had no damaging effect on glandular epithelial cells. After 8 to 16 hours of hypoxia, glandular secretion was reduced and the epithelial cells were evacuated. From the findings of the present investigation it is concluded that the decrease in the production of protective intestinal juice, due to the damaging effect of hypoxia on the epithelium and glandular epithelium as well as on the mitochondria, and the increase in the absorption of the intestinal content should be considered responsible of the additional damages to the intestinal epithelium.