Changes of HDL subfraction concentration and particle size by intralipid in vivo

Abstract

The effects of the artificial triglyceride-phospholipid emulsion (10% intralipid) on HDL subfraction were studied in vivo. After a 14-h fast, subjects received intralipid via a 4-h infusion. Serum lipoproteins were analyzed before and at 4 and 6 h after the start of the infusion. At 4-h the following acute changes by infusion were observed. Triglyceride, phospholipid, free cholesterol, and esterified cholesterol in chylomicrons and VLDL increased. HDL 2 as well as triglyceride, phospholipid, free cholesterol and protein within the HDL 2 increased, while HDL 3 decreased. An increase in HDL 3 triglyceride was observed. The masses of apo A-I and A-II in the HDL 2 density interval rose while these parameters fell in HDL 3. There were decreases of apo C-II and C-III in the HDL subfractions and elevations in chylomicrons and VLDL. The particle size of the HDL subfractions increased. However, most of these acute changes at 4 h tended to disappear by 6 h. These results suggest that there is exchange of lipids and reversible transfer of apo C-II and C-III between HDL subfractions and intralipid, and conversion of HDL 3 to HDL 2 followed by the reverse conversion of HDL 2 to HDL 3 as the synthetic emulsion is cleared from the plasma.