Endogenous fatty acids in alimentary triglyceridemia in normolipemic young males

Abstract

The contribution of endogenous triglyceride fatty acids (TGFA) in alimentary lipemia was studied in ten normolipemic males under 26 years. Serum, drawn before and during absorption of 50 ml of corn oil, was separated by ultracentrifugation into two fractions, one containing chylomicrons (Sf is less than 400), the second containing all other lipoproteins (Sf is less than 400). The percent of dietary triglyceride fatty acid in each fraction of the postprandial samples was calculated using triglyceride fatty acid percent composition patterns in the meal and each fraction of the fasting and postprandial samples. Corn oil was chosen for the meal because it differs considerably from fasting serum in percent of palmitic (16:0) and linoleic (18.2) acids. The endogenous triglyceride fatty acid in the chylomicron fraction remained constant during the absorption period, while the dietary triglyceride fatty acids reached a peak level of 63 percent of the total at 4 hours and decreased to 50 percent by 8 hours. In the nonchylomicron lipoprotein fraction, the dietary triglyceride fatty acids increased throughout the test period to 29 percent of total triglyceride fatty acids at 8 hours. At 2 hours endogenous triglyceride fatty acids showed a slight increase relative to the fasting level, then decreased continuously at a slow rate so that by 8 hours it was below the fasting level. These data suggest that during alimentary triglyceridemia, dietary triglyceride fatty acies incorporated into chylomicrons during absorption are rapidly released in the serum as free fatty acids and subsequently utilized in hepatic lipoprotein production and secretion. The data also indicate that circulating endogenous triglyceride fatty acids play a role in alimentary triglyceridemia by remaining essentially constant during early and peak periods and then decreaseing to aid in the subsequent recovery.