BACKGROUND: Triglyceride-rich lipoprotein remnants are atherogenic, and this may be particularly important in visceral obesity. We investigated remnant metabolism in obese men by measuring remnant-like particle-cholesterol (RLP-C), apolipoprotein (apo) B-48, apoC-III, and the clearance of a labeled remnant-like emulsion. METHODS: Fasting RLP-C, apoB-48, and apoC-III concentrations were measured in 48 viscerally obese men and 10 lean controls. RLP-C was determined by immunoseparation assay, apoB-48 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and enhanced chemiluminescence, and apoC-III by immunoturbidimetric assay. The catabolism of chylomicron remnants was measured by intravenous injection of a remnant-like emulsion containing cholesteryl [(13)C]oleate, with isotopic enrichment of (13)CO(2) in breath determined by isotope-ratio mass spectrometry and a multicompartmental model to estimate fractional catabolic rate (FCR) of the emulsion. RESULTS: Compared with controls, obese men had significantly increased plasma concentrations of RLP-C, apoB-48, and apoC-III (P <0.001 for all). Plasma total apoB-100, non-HDL-cholesterol, LDL-cholesterol, triglycerides, and insulin resistance (HOMA score) were also significantly higher in the obese group (P <0.001 for all). Obese men had a significantly lower FCR of the remnant-like emulsion compared with controls (P = 0.020). CONCLUSIONS: Viscerally obese individuals have insulin resistance and increased plasma concentrations of triglyceride-rich lipoprotein remnants, which may be attributable to decreased catabolism of these particles.
BACKGROUND: Triglyceride-rich lipoprotein remnants are atherogenic, and this may be particularly important in visceral obesity. We investigated remnant metabolism in obesemen by measuring remnant-like particle-cholesterol (RLP-C), apolipoprotein (apo) B-48, apoC-III, and the clearance of a labeled remnant-like emulsion. METHODS: Fasting RLP-C, apoB-48, and apoC-III concentrations were measured in 48 viscerally obesemen and 10 lean controls. RLP-C was determined by immunoseparation assay, apoB-48 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and enhanced chemiluminescence, and apoC-III by immunoturbidimetric assay. The catabolism of chylomicron remnants was measured by intravenous injection of a remnant-like emulsion containing cholesteryl [(13)C]oleate, with isotopic enrichment of (13)CO(2) in breath determined by isotope-ratio mass spectrometry and a multicompartmental model to estimate fractional catabolic rate (FCR) of the emulsion. RESULTS: Compared with controls, obesemen had significantly increased plasma concentrations of RLP-C, apoB-48, and apoC-III (P <0.001 for all). Plasma total apoB-100, non-HDL-cholesterol, LDL-cholesterol, triglycerides, and insulin resistance (HOMA score) were also significantly higher in the obese group (P <0.001 for all). Obesemen had a significantly lower FCR of the remnant-like emulsion compared with controls (P = 0.020). CONCLUSIONS:Viscerally obese individuals have insulin resistance and increased plasma concentrations of triglyceride-rich lipoprotein remnants, which may be attributable to decreased catabolism of these particles.