High density lipoproteins in postprandial lipemia. Relation to sex and lipoprotein lipase activity.

Twelve subjects (6 women, 6 men) were given 120 g fat orally for 2 h to study its effect on serum high density lipoproteins (HDL), HDL subfractions and apoproteins A-I and A-II. In addition, we measured the fasting activity of adipose tissue lipoprotein lipase (LPL). The HDL2 mass concentration increased significantly in women (216 +/- 10 vs 232 +/- 12 mg/dl, P less than 0.01) but not in men (114 +/- 10 vs 119 +/- 11 mg/dl, NS). The changes of the HDL2 mass in women were due to significant increases of phospholipids, and both apoproteins A-I and A-II. In men, only HDL2 phospholipids rose slightly. The HDL2 cholesterol remained unchanged postprandially. Both fasting and maximal postprandial concentrations of HDL2 correlated positively with adipose tissue LPL activity (r = +0.63, P less than 0.05 and r = +0.61, P less than 0.05). The concentration of HDL3 remained unchanged postprandially but compositional changes were observed. Thus, the HDL3 phospholipids increased slightly in both sexes whereas the HDL3 cholesteryl esters fell significantly. The postprandial changes of HDL2 and HDL3 phospholipids were evident in both zonal ultracentrifugation and equilibrium ultracentrifugation. In addition, 5 women received intragastric fat infusions with or without extra soya phospholipids, lecithin. The HDL2 mass concentration increased after both infusions. In 4 of the 5 subjects the overall increment of the HDL2 phospholipids was larger after the phospholipid-rich emulsion than after phospholipid-poor one. This difference was obvious in zonal profile of HDL subfractions which revealed also a slight increase of HDL3 phospholipids after both infusions. In conclusion, the response of HDL2 to fat meal is more pronounced in women than in men and it seems to be dependent on fasting LPL activity which is higher in women than in men. Further, the alterations in postprandial composition of HDL subfractions can be modified by the composition of fat meal.