title: Plasma apolipoprotein B-48 transport in obese men: a new tracer kinetic study in the postprandial state.
abstract: BACKGROUND
  The mechanisms responsible for impaired chylomicron metabolism have not been adequately investigated in obese subjects.
  
  
  OBJECTIVE
  We aimed to compare apolipoprotein (apo) B-48 kinetics in obese and lean men by developing a new model to describe the kinetics of apoB-48 particles in the postprandial state.
  
  
  METHODS
  Seven obese and 13 age-matched lean men were given an oral fat load. apoB-48 tracer to tracee ratios were measured after intravenous d3-leucine administration using gas chromatography-mass spectrometry. Kinetic parameters were derived using a multicompartmental model.
  
  
  METHODS
  Plasma total and incremental apoB-48 0-10 hour areas under the curve as well as apoB-48 secretion and fractional catabolic rate.
  
  
  RESULTS
  Compared with lean men, fasting plasma triglyceride (+148%) and apoB-48 (+110%) concentrations as well as plasma total and incremental triglycerides (+184% and +185%, respectively) and apoB-48 (+182% and 224%, respectively) areas under the curve were significantly higher in obese men (P<.05 for all). The obese men also had significantly (P<.05 for all) higher secretion rates of apoB-48 in the fasted state (+145%) as well as at 3 hours (+70%), 4 hours (+82%), 5 hours (+82%), 6 hours (+76%), and 8 hours (+61%) in response to the fat load. This was associated with a greater number of apoB-48-containing particles secreted over the 10-hour study period in the obese men, compared with lean men (+125%, P<.01). The fractional catabolic rate of apoB-48 was significantly lower in the obese men compared with the lean men (-33%, P<.05) CONCLUSION: We demonstrate that postprandial hypertriglyceridemia in central obesity relates to an overproduction and impaired catabolism of apoB-48-containing lipoproteins. These findings are based on a new, physiologically relevant, kinetic model, which describes the non-steady-state postprandial metabolism of apoB-48.
authors.affiliation: School of Medicine and Pharmacology (A.T.Y.W., D.C.C., J.P., G.F.W., P.H.R.B.) and Faculty of Engineering, Computing, and Mathematics (P.H.R.B.), University of Western Australia, Perth, Western Australia 6847, Australia.
authors.forename: Annette T Y
authors.initials: AT
authors.lastname: Wong
authors.forename: Dick C
authors.initials: DC
authors.lastname: Chan
authors.forename: Jing
authors.initials: J
authors.lastname: Pang
authors.forename: Gerald F
authors.initials: GF
authors.lastname: Watts
authors.forename: P Hugh R
authors.initials: PH
authors.lastname: Barrett
mesh_terms: D000368:Aged; D053283:Apolipoprotein B-48 / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D007700:Kinetics; D007930:Leucine / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism*; D019518:Postprandial Period / Q000502:physiology; D021381:Protein Transport; D011849:Radioactive Tracers; D013851:Thinness / Q000378:metabolism
chemical_list: D053283:Apolipoprotein B-48; D001798:Blood Proteins; D011849:Radioactive Tracers; D007930:Leucine