Comparison between cholesterol and phosphatidylcholine intestinal absorption from native bile labelled with [1-2 3H] cholesterol and [1-14C] palmitic acid in the rat
Reisser, D.; Boquillon, M.; Clément, J.
Journal de Physiologie 76(8): 865-870
1980
ISSN/ISBN: 0021-7948 PMID: 7241396 Document Number: 157978
Intestinal absorption of labeled cholesterol and phosphatidylcholines from native bile was studied. Labeled native bile was collected from rats after i.v. injection of K [1-14C] palmitate and [1-2 3H] cholesterol. A group of recipient rats, without bile fistula, was intraduodenally injected with 0.5 ml of this bile and sacrificed 1 h later. Another group of rats, with a bile fistula, was intraduodenally infused with 0.6 ml of this bile per hour for 6 h and then sacrificed. Some of the latter rats had lymph fistula and were sacrificed 24 h after the beginning of the infusion of bile. When the bile infusion was stopped, an infusion of solution glucose-NaCl was given until sacrifice. Analyses were carried out on different sites on the digestive tract, lymph (chylomicrons and infranatant) and bile of recipient rats. Labeled biliary cholesterol and phosphatidylcholines were absorbed in the proximal part of the small intestine. The proportions of lipidic [3H] and [14C] radioactivity which disappeared from the contents of the small intestine were similar during 1 h in rats without bile fistula. In rats with bile fistula and infused with radioactive bile for 6 h, modifications of luminal composition of labeled lipids occurred and, in particular, [3H] labeled sterol disappeared more slowly than [14C] labeled lipids. In the mucosa of the 2 groups of rats, [3H] cholesterol was recovered in greater amounts than [14C] lipids, mostly in the proximal part of the small intestine; mucosal triglycerides were highly radioactive. In lymphatic chylomicrons, the proportions of lipidic [14C] radioactivity (chiefly present as triglycerides) were always higher than those of [3H] cholesterol as compared to infused [14C] and [3H] radioactivity. The [14C] labeling of phosphatidylcholines was higher in infranatant than in chylomicrons.