THE EFFECT OF APOLIPOPROTEIN-E ISOFORM DIFFERENCE ON POSTPRANDIAL LIPOPROTEIN COMPOSITION IN PATIENTS MATCHED FOR TRIGLYCERIDES, LDL-CHOLESTEROL, AND HDL-CHOLESTEROL

The postprandial response to three test meals provided during a single day was investigated in subjects with either the apo E3/3 phenotype (n = 8), or the apo E4/3 phenotype (n = 4), who had LDL-C greater than 160 mg/dl. Vitamin A (60,000 U/m2) was ingested with the first meal and retinyl palmitate determined four hours later. Triglyceride and total cholesterol concentration were determined on whole plasma and total cholesterol and free cholesterol determined following single spin ultracentrifugation (d < 1.006 g/ml) and dextran precipitation of the d > 1.006 fraction to separate apoprotein-B containing lipoproteins. Fasting values revealed significantly lower HDL-cholesterol ester (p < 0.03) and HDL3-cholesterol ester (p < 0.03) and significantly greater HDL-free cholesterol (p < 0.03) and HDL3-free cholesterol (p < 0.02) in subjects with the E4/3 phenotype. Four hour postprandial HDL and HDL3 cholesterol ester increased significantly more (p < 0.05) in E4/3 patients and HDL and HDL3 free cholesterol decreased significantly more (p < 0.05) in E4/3 subjects. Eight-hour postprandial change values maintained the significant HDL3-cholesterol ester and free cholesterol difference, and, revealed a significantly greater triglyceride rich lipoprotein cholesterol ester reduction (p < 0.01) in the E4/3 group. Individuals with the apolipoprotein E4/3 phenotype reveal significant differences in postprandial lipemia compared to individuals with the E3/3 phenotype, and, postprandial lipemia following multiple meals reveals differences not apparent from responses to a single meal.