Determinants of LDL subfraction distribution and concentrations in young normolipidemic subjects.

Human low-density lipoproteins (LDLs) comprise a spectrum of particles that vary in size, density, chemical composition, metabolic behavior, and atherogenicity. To identify determinants of this heterogeneity, we measured the percent distribution and plasma concentration of the three major LDL subfractions in 34 young healthy subjects. These parameters were correlated in univariate and multivariate analyses with various body and lifestyle factors; plasma lipids and lipoprotein; and the activities of cholesteryl ester transfer protein, lipoprotein lipase, and hepatic lipase (HL). Women (n = 15) had significantly more large, buoyant LDL (LDL-I; density, 1.025 to 1.034 g/mL) and high-density lipoprotein2 (HDL2) than men (n = 19). Both the percentage and concentration of LDL-I were correlated negatively with very-low-density lipoprotein triglycerides (VLDL-TG) and HL; they were correlated positively with HDL-cholesterol (HDL-C) and HDL2. In addition, percent LDL-I was negatively correlated with plasma triglycerides, VLDL-C, LDL-C, and apo-lipoprotein (apo) B concentrations. The concentrations of intermediate and small, dense LDL (LDL-II and LDL-III; density, 1.034 to 1.044 and 1.044 to 1.060 g/L, respectively) were positively correlated with LDL-C. LDL-III concentrations were also related to plasma cholesterol and apoB concentrations and HL activity. On multivariate analyses, approximately one third of the variability in LDL-I was explained by HL and plasma triglycerides. More than 80% of the variation in LDL-II was accounted for by a model that combined LDL-C and plasma apoB with body mass index and VLDL-TG.(ABSTRACT TRUNCATED AT 250 WORDS)