Plasma apolipoprotein B-48 transport in obese men: a new tracer kinetic study in the postprandial state.

Abstract

CONTEXT:

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.

DESIGN, SETTING, AND PATIENTS:

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.

OUTCOMES MEASURES:

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: Annette T Y Wong, Dick C Chan, Jing Pang, Gerald F Watts, P Hugh R Barrett
• Journal: The Journal of clinical endocrinology and metabolism (J Clin Endocrinol Metab) Vol. 99 Issue 1 Pg. E122-6 (Jan 2014) ISSN: 1945-7197 [Electronic] United States
• PMID: 24203058 (Publication Type: Controlled Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Apolipoprotein B-48
• Blood Proteins
• Radioactive Tracers
• Leucine

Topics

• Aged
• Apolipoprotein B-48 (metabolism)
• Blood Proteins (metabolism)
• Humans
• Isotope Labeling (methods)
• Kinetics
• Leucine (pharmacokinetics)
• Male
• Middle Aged
• Obesity (metabolism)
• Postprandial Period (physiology)
• Protein Transport
• Radioactive Tracers
• Thinness (metabolism)