Triacylglycerol and cholesterol transport during absorption of glycerol trioleate vs. glycerol trielaidate.

We used conscious, chronic lymph-fistula rats to compare intestinal lymphatic transport of glycerol trioleate (TO) vs. glycerol trielaidate (TE) and to determine the effect of TO vs. TE on absorption and transport of cholesterol. Rats were implanted with intestinal lymph fistulas and duodenal cannulas and then given intraduodenal infusions of lipid emulsions containing purified TO or TE (40 mumol/h) and cholesterol (7.8 mumol/h + 2 microCi [14C]cholesterol). Lymph samples were collected at 0, 2, 4, 5, 6, 7, and 8 h after the start of lipid infusion. Lymphatic output and luminal and gut wall recovery of radioactive lipid at 8 h were quantified. Triacylglycerol (TG) fatty acid isomers did not affect lymphatic output of TG; lymph TG fatty acid composition and output reflected infusate composition. Lymphatic output of cholesterol (mass and radioactivity) did not differ between groups; luminal and gut wall recovery of [14C]cholesterol was also similar between groups. Similar lymphatic transport of TG and cholesterol between triolein- and trielaidin-infused rats was maintained for up to 16 h after the cessation of an infused lipid load. These results indicate that TO and TE are transported into lymph similarly, and that cholesterol absorption and transport are similar irrespective of whether TO or TE is the TG source. The data suggest that trans fatty acid-induced hypercholesterolemia is not due to altered intestinal absorption and transport of cholesterol.