HIGH-DENSITY-LIPOPROTEINS WITH DIFFERING APOLIPOPROTEINS - RELATIONSHIPS TO POSTPRANDIAL LIPEMIA, CHOLESTERYL ESTER TRANSFER PROTEIN, AND ACTIVITIES OF LIPOPROTEIN-LIPASE, HEPATIC LIPASE, AND LECITHIN-CHOLESTEROL ACYLTRANSFERASE

To gain insight into metabolic determinants of high density lipoprotei ns (HDL) containing apolipoproteins A-I and A-II (LpA-I/A-II) and thos e containing A-I, but devoid of A-II (LpA-I), the plasma concentration of LpA-I and LpA-I/A-II within the HDL(2) and HDL(3) density spectrum was measured in 14 normolipidemic male subjects on a standardized die t. Apolipoprotein plasma concentrations of HDL subspecies were compare d with the magnitude of postprandial lipemia, activities of lipoprotei n lipase and hepatic lipase in postheparin plasma, plasma lecithin:cho lesterol acyltransferase (LCAT) activity, and cholesteryl ester transf er protein (CETP) mass. Plasma levels of LpA-I/A-II were 2.5 times hig her than levels of LpA-I (123 +/- 20 vs. 48.3 +/- 22.1 mg protein/dl) and the partition of LpA-I and LpA-I/A-II between HDL(2) and HDL(3) di ffered in that the proportion of LpA-I associated with HDL(2) was grea ter than that of LpA-I/A-II (23 +/- 19 vs. 6 +/- 6%, P < 0.002). With increasing levels of HDL(2), the proportion of LpA-I in HDL(2) increas ed (P < 0.002). Furthermore, levels of LpA-I and LpA-I/A-II were stron gly correlated within the HDL(2), but not within the HDL(3) density re gion. Plasma levels of LpA-I, but not LpA-I/A-II, were inversely corre lated with the magnitude of postprandial lipemia. However, activities of lipoprotein lipase and hepatic lipase tended to show stronger assoc iations with the partition of LpAI/A-II between HDL(2) and HDL(3) than with that of LpA-I. Within the HDL(3), but not the HDL(2) density spe ctrum, LpA-I/A-II exhibited a positive association with plasma LCAT ac tivity, while LpA-I displayed an inverse association with plasma CETP mass. These results are consistent with differences in substrate prope rties of LpA-I and LpA-IIA-II for lipoprotein-modifying enzymes and im ply different, but overlapping metabolic pathways of LpA-I and LQA-I/A -II.