Effect of apolipoprotein E3/4 phenotype on postprandial triglycerides and retinyl palmitate metabolism in plasma from hyperlipidemic subjects in Japan

In a previous study it was shown that postprandial lipid metabolism is dela yed in individuals with intra-abdominal visceral fat accumulation. Populati on studies have shown that as compared with individuals with apolipoprotein (apo) E3/3, those with phenotype apo E3/4 phenotype have higher plasma and low density lipoprotein (LDL)-cholesterol (C) concentration acid increased susceptibility to coronary heart disease. The aim of the present study is to determine how apo E4 affects postprandial lipid metabolism by comparing individuals with apo E3/4 to those with apo E3/3 phenotype matched for abdo minal visceral fat. Sixty-two Japanese subjects (41 male, 21 female) [avera ge age 48 +/- 14 years; mean body mass index (BMI) 25 +/- 5.6 kg/m(2)] were recruited for this study. The subjects were divided into two groups: those with apo E3/3 (n = 43) and those with apo E3/4 phenotype (n = 19), as dete rmined by isoelectric focusing (IEF). Visceral fat accumulation was analyze d as area of fat deposition by computerized tomography at the umbilicus lev el. After a 12-h overnight fasting, an oral vitamin A and a fatty meal were administered to these subjects. The plasma triglyceride (TG) increased sig nificantly hours after fat loading in both groups but the levels of TG were significantly higher in apo E3/4 than in apo E3/3 phenotype at 2, 4 and 6 h after fat loading. Plasma retinyl palmitate (RP) levels were also signifi cantly higher in individuals with apo E3/3 than in those with apo E3/3 phen otype at 2, 4 and 6 h after fat loading. This investigation was then conduc ted in both genders separately, and found that these associations were stat istically significant in men. Furthermore, after matching men for fasting T G levels, these associations did not persist for plasma TG levels at any ti me point, while plasma RP levels were still significantly higher in apo E3/ 4 group at 2 and 6 h after fat loading. These results indicate that in Japa nese population especially for men apo E phenotype E3/4 is associated with an impaired postprandial TG-rich lipoprotein metabolism relative to apo E3/ 3 phenotype when matched for intra-abdominal visceral fat accumulation, whi ch has a substantial effect on the metabolism of plasma TG-rich lipoprotein s. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.