title: A study of the metabolism of apolipoprotein B100 in relation to insulin resistance in African American males.
abstract: The purpose of this study was to determine the relationship between insulin resistance and apoB100 metabolism in African American males. Fifteen subjects, 33 +/- 7.6 years old, were divided into two groups, insulin-resistant (IR) or insulin-sensitive (IS), based on the sum of the plasma insulin concentrations during an oral glucose tolerance test. The IR group (n = 8) differed significantly from the IS group (n = 7) with respect to body mass index (BMI) (30.1 vs 23.1 kg/m2; P = 0.0003), fasting triglycerides, (118 vs 54 mg/dl, P = 0. 013), and total plasma apolipoprotein B100 (80 vs 59 mg/dl, P = 0.014). Significantly elevated apoB100 levels in the IR group were seen in very low density lipoprotein (VLDL) (5.1 vs 3.4 mg/dl, P = 0.045) and intermediate density lipoprotein (IDL) (18 vs 12 mg/dl, P = 0.017) but not in low density lipoprotein (LDL) (57 vs 46 mg/dl, P = 0.19). Total cholesterol, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), apolipoprotein A-I, and blood pressure were not significantly different between the two groups. There was a high correlation between the sum of insulins during the oral glucose tolerance test and the BMI (rho = 0.88, P = 0.0001). In five IR and five IS subjects, apoB100 kinetics were determined in the fasting state using a bolus dose of deuteroleucine and multicompartmental modeling. IR subjects had significantly lower fractional catabolic rates (FCR) in the larger VLDL1 (-70%), the smaller VLDL2 (-71%), and the IDL (-53%) fractions. No significant differences in production rates were observed for any lipoprotein class. There was a significant correlation between the sum of insulins and the FCR of the apoB100 of VLDL1 (rho = -0.65, P = 0.05) and of IDL (rho = -0.85, P = 0.004). The correlation coefficient of the sum of insulins and the FCR of VLDL2 was -0.61 with P = 0.067. We conclude that in this population of African American males, IR is correlated with a decreased FCR of apoB100 in VLDL and IDL and elevated plasma levels of apoB and triglycerides (TG). These changes might be explained by decreased clearance of the TG-rich lipoproteins. We postulate that this may reflect decreased lipoprotein and/or hepatic lipase activity related to insulin resistance and its association with obesity.
authors.affiliation: Department of Biochemistry, MCP-Hahnemann University School of Medicine, Philadelphia, Pennsylvania 19129, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Sumner
authors.forename: B
authors.initials: B
authors.lastname: Falkner
authors.forename: M R
authors.initials: MR
authors.lastname: Diffenderfer
authors.forename: P H
authors.initials: PH
authors.lastname: Barrett
authors.forename: J B
authors.initials: JB
authors.lastname: Marsh
mesh_terms: D000328:Adult; D053299:Apolipoprotein B-100; D001055:Apolipoproteins B / Q000378:metabolism*; D044383:Black People; D015992:Body Mass Index; D002784:Cholesterol / Q000097:blood; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D007700:Kinetics; D007930:Leucine / Q000097:blood / Q000493:pharmacokinetics; D008077:Lipoproteins, LDL / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood; D008297:Male; D008875:Middle Aged; D001741:Black or African American
chemical_list: D053299:Apolipoprotein B-100; D001055:Apolipoproteins B; D007328:Insulin; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D002784:Cholesterol; D007930:Leucine