Adipose tissue compartments and the kinetics of very-low-density lipoprotein apolipoprotein B-100 in non-obese men

Abstract

We examined the association between the kinetics of very-low-density lipoprotein (VLDL) apolipoprotein B-100 (apoB) and intraperitoneal, retroperitoneal, subcutaneous abdominal, and total adipose tissue masses (IPATM, RPATM, SAATM, TATM, respectively) in 14 healthy, non-obese men (body mass index [BMI] < 30 kg/m(2)). Hepatic secretion of VLDL-apoB was measured using an intravenous infusion of 1-[(13)C]-leucine. Isotopic enrichment of VLDL-apoB was measured using gas chromatography-mass-spectrometry and a multicompartmental model (Simulation, Analysis, and Modeling Software [SAAM II]) used to estimate the fractional catabolic rate (FCR) of VLDL-apoB. IPATM, RPATM, and SAATM (kg) were quantified between T11 and S1 using magnetic resonance imaging (MRI); TATM (kg) was determined using bioelectrical impedance. Insulin resistance was estimated by homeostasis model assessment (HOMA) score. In stepwise regression analysis, IPATM was the best predictor of the hepatic secretion of VLDL-apoB (r =.58, P <.05) and TATM the best predictor of the FCR of VLDL-apoB (r = -.56, P <.05). After adjusting for TATM, IPATM explained 59% of the variance in VLDL apoB secretion (P =.03). None of the fat compartments were significantly associated with VLDL-apoB kinetics after adjusting for HOMA score. The findings suggest that in non-obese men the quantity of both intraperitoneal and total fat are significant predictors for the kinetics of VLDL-apoB, which in turn, determines plasma triglyceride concentrations; these associations may, in part, be mediated by variations in insulin resistance, particularly among individual who are not ostensibly obese. Our preliminary results need confirmation in a larger study.