Uptake of micellar lipids by small intestinal segments (under different experimental conditions).

Abstract

AbstractUptake of radioactive cholesterol, sitosterol and monoolein from micellar solutions was studied under different conditions in rat small intestinal segments both with and without blood supply, and in inverted segments in vitro. The Na+/K+ ratio of the micellar test solution did not influence the uptake of any species of lipid tested. In vivo the uptake of sterols was maximal at 37°C. It had a Q10 of about 3. Three states of sterol uptake were observed. (1) A high uptake of both cholesterol and sitosterol, (2) a low uptake of both sterols, and (3) a low uptake of sitosterol with a high uptake of cholesterol. The latter state corresponds to normal uptake in vivo. These states were demonstrated under different experimental conditions involving exclusion of blood supply to the small intestine, extensive hypothermic treatment of the rat, extensive hypothermic treatment followed by rewarming to 37°C, and biliary drainage followed by uptake experiments with high concentrations of NaTDC or NaTC. It was demonstrated that the normal uptake of sterols could be both irreversibly and reversibly changed into the other abnormal states of uptake.