title: Apolipoprotein B-48 and retinyl palmitate are not equivalent markers of postprandial intestinal lipoproteins.
abstract: This study compared retinyl palmitate and apolipoprotein (apo) B-48 as markers of postprandial triglyceride-rich lipoproteins. Nine non-diabetic men received an oral vitamin A-containing fat load. We measured retinyl palmitate, apoB-48, apoB-100, and triglyceride levels in Sf > 400, Sf 60-400 and Sf 20-60 lipoproteins. The peak retinyl palmitate concentration was delayed compared to the peak apoB-48 concentration in each fraction. The discrepancy between retinyl palmitate and apoB-48 was further investigated in another study of 12 men. In that study, a fat load was given and 5 h later, lipolysis was stimulated in vivo with heparin (60 U/kg, i.v.) and the same parameters were followed. Thirty minutes after heparin, triglyceride levels decreased significantly in the three triglyceride-rich lipoprotein fractions (Sf > 400, Sf 60-400 and Sf 20-60). ApoB-48 levels also fell significantly in the three triglyceride-rich lipoprotein fractions. In contrast, retinyl palmitate concentrations did not change significantly in Sf > 400 and Sf 60-400 fractions and increased significantly in the Sf 20-60 fraction. Our results indicate that retinyl palmitate and apolipoprotein B-48 do not mark the same properties of postprandial intestinal lipoproteins. The metabolic pattern of apolipoprotein B-48 parallels that of triglyceride. One possible explanation for these observations is that the apoB-48-containing triglyceride-rich lipoproteins are metabolically heterogeneous and that older particles, those in circulation for a longer period of time, may be cleared more rapidly than newer ones.
authors.affiliation: WHO Collaborating Center for the Study of Atherosclerosis in Diabetes and the Department of Medicine, The Toronto Hospital (General Division), University of Toronto, Ontario, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Lemieux
authors.forename: R
authors.initials: R
authors.lastname: Fontani
authors.forename: K D
authors.initials: KD
authors.lastname: Uffelman
authors.forename: G F
authors.initials: GF
authors.lastname: Lewis
authors.forename: G
authors.initials: G
authors.lastname: Steiner
mesh_terms: D000328:Adult; D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B / Q000097:blood*; D015415:Biomarkers; D004041:Dietary Fats / Q000008:administration & dosage; D004224:Diterpenes; D005215:Fasting; D005502:Food; D006493:Heparin / Q000008:administration & dosage; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D007700:Kinetics; D008074:Lipoproteins / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D000084562:Retinyl Esters; D014280:Triglycerides / Q000097:blood; D014801:Vitamin A / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B; D015415:Biomarkers; D004041:Dietary Fats; D004224:Diterpenes; D008074:Lipoproteins; D000084562:Retinyl Esters; D014280:Triglycerides; D014801:Vitamin A; C014794:retinol palmitate; D006493:Heparin