ROLE OF THE INTESTINE IN CHYLOMICRON REMNANT CLEARANCE

When 810 mu mol of [H-3]glyceryl trioleate (TO) were infused intraduod enally over 6 h into rats, 29% of the triacylglycerol (TG) acyl groups in the mucosa were not from the infusate. We tested the hypothesis th at chylomicron remnants contribute to the mucosal pool of nondietary T G acyl groups, since the acyl group composition of the chylomicron rem nants was 58% oleate, compared with 90% in their parent chylomicrons. Purified H-3-labeled remnants were generated from chylomicrons formed in rats receiving TO intraduodenally, with 95% of the remnant disinteg rations per minute (dpm) being in TG. The H-3-remnants were infused in travenously into rats receiving either saline or 135 mu mol/h TO intra duodenally. In the saline-infused rats, 32% of the infused H-3 dpm wer e in the proximal and 19% in the distal intestine and 32% were in the liver. In the fat-infused rats, 12% of the infused 3H dpm were in the proximal and 5% were in the distal gut and 29% were in the liver. When [H-3]cholesterol-labeled remnants were infused intravenously and sali ne was infused intraduodenally, the percentage uptake into the mucosa was nearly the same as with the TG label, but comparable uptake by the liver increased. We conclude that the intestine competes with the liv er for chylomicron remnant TG and cholesterol.