Contribution of apoB-48 and apoB-100 triglyceride-rich lipoproteins (TRL) to postprandial increases in the plasma concentration of TRL triglycerides and retinyl esters.
After the ingestion of a fat-rich meal, there is a postprandial increase in the plasma concentration of both apolipoprotein B-48- and apoB-100-containing triglyceride-rich lipoproteins (apoB-48 and apoB-100 TRL). In order to determine the contribution of these lipoproteins to postprandial lipemia, the concentration of triglycerides (TG) and retinyl esters (RE) was measured in apoB-48 and apoB-100 TRL after an oral fat load. Six normolipidemic male subjects were fed heavy cream (1 g fat per kg body weight) containing vitamin A (3000 retinol equivalents). TRL were isolated by ultracentrifugation from plasma samples obtained at regular intervals after the meal, and apoB-100 TRL were separated from apoB-48 TRL by affinity chromatography using monoclonal antibodies. Postprandial increase in plasma TG concentration was due to an increase in TG in the TRL fraction, which in turn was predominantly (82 +/- 4%) due to an increase in TG in apoB-48 TRL. Contribution of apoB-100 TRL to postprandial increase in TRL TG was 3-27% in individual subjects. ApoB-100 TRL remained a significant carrier of total plasma triglyceride in the fed state, as reflected by similar apoB-100 and apoB-48 TRL TG concentrations at 2, 4, and 6 h after the fat meal. Retinyl esters were regularly detected in apoB-100 TRL. Seventy-five (+/- 9) percent of the increase in TRL-RE was due to RE in apoB-48 TRL and 25 +/- 9% was due to RE in apoB-100. These data suggest that RE in plasma are not always associated with apoB-48-containing lipoproteins.(ABSTRACT TRUNCATED AT 250 WORDS)
Cohn
J S
JS
Lipid Metabolism Laboratory, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111.
Johnson
E J
EJ
Millar
J S
JS
Cohn
S D
SD
Milne
R W
RW
Marcel
Y L
YL
Russell
R M
RM
Schaefer
E J
EJ
D000328:Adult; D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B / Q000378:metabolism*; D002784:Cholesterol / Q000097:blood; D004041:Dietary Fats / Q000008:administration & dosage*; D005215:Fasting; D005502:Food; D006801:Humans; D007700:Kinetics; D008297:Male; D014280:Triglycerides / Q000097:blood*; D014801:Vitamin A / Q000097:blood*
D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B; D004041:Dietary Fats; D014280:Triglycerides; D014801:Vitamin A; D002784:Cholesterol