Chylomicron composition during duodenal triglyceride and lecithin infusion.

In lymph fistula rats infused intraduodenally with trioleoylglycerol emulsions, the secretion of triglyceride was enhanced and that of total and esterified cholesterol in chylomicrons was strikingly reduced when lecithin was added at 4-5 times the biliary lecithin secretion rate. During continued triglyceride secretion in the presence of lecithin, the phospholipid: unesterified cholesterol ratio of the chylomicrons increased significantly in contrast to lecithin-free emulsions. Bile-diverted lymph fistula rats secreted significantly less esterified and total cholesterol in lymph chylomicrons than controls, and the difference was magnified by lecithin administration. Cholesterol appears to become relatively unavailable for incorportion into chylomicrons when lecithin is administered at high rates.