Effect of mixed micellar lipid on the absorption of cholesterol and vitamin D<sub>3</sub> into lymph

Gilbert R. Thompson; Robert K. Ockner; Kurt J. Isselbacher

doi:10.1172/JCI105977

Effect of mixed micellar lipid on the absorption of cholesterol and vitamin D₃ into lymph

Gilbert R. Thompson, Robert K. Ockner, and Kurt J. Isselbacher

Published January 1, 1969 - More info

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Abstract

The absorption of endogenous cholesterol, labeled with tracer doses of cholesterol ¹⁴C or cholesterol-³H and of near physiological doses of vitamin D₃-³H was studied in rats with cannulated intestinal lymphatics. The effects of administering mixed micellar solutions of fatty acid, monoglyceride, and bile salt on the absorption of these labeled sterols was determined. It was observed that the specific activity of free cholesterol and the amounts of vitamin D₃ appearing in lymph were significantly increased during the intraduodenal administration of mixed micellar solutions of either linoleic or palmitic acid, in contrast to control rats receiving a micellar solution of taurocholate. These increases were related linearly to the lymph triglyceride level. In addition it was observed that when the linoleic acid solution was administered there was a more marked increase in the ratio of the specific activities of free and esterified cholesterol in lymph than with either the palmitic acid or taurocholate solutions.

Additional studies in rats with intact lymphatics showed that the uptake of labeled cholesterol and vitamin D₃ from the intestinal lumen into the wall was similar whether the sterols were administered in taurocholate or in mixed micellar solution.

These findings suggest that mixed micellar lipid increased the rate of appearance of labeled free cholesterol and vitamin D₃ in lymph by enhancing their transport out of the intestinal mucosa, rather than by an effect on uptake.