Fat loading experiments with the vitamins A and E suggest that in postprandial lipemia transfer/diffusion of chylomicron lipids to VLDL contributes to beta-VLDL formation.
Vitamins A and E differ in hydrophobicity. When added to a fat load more or less specific labeling of chylomicrons and their remnants can be expected and this allows to approach the mechanism of postprandial lipemia from a new sight of view. Applied in a study in which 20 patients participated (eight patients with familial dysbetalipoproteinemia (FD), six patients with familial combined hyperlipidemia (FCH) and six controls) we found that vitamin A, no longer paralleled the apo B-48 concentrations from 9 h after a fat load, especially in the remnant fraction with Sf 15-100. Qualitatively, the distribution of vitamin A to the more dense fractions mirrored that of vitamin E, but the latter was more rapid. Both vitamins at the maximum of remnant-accumulation, at 14 h after the fat load, correlated with the cholesterol content of the remnant fraction. For vitamin E there was a similar concentration dependent distribution to all other lipoprotein fractions. The results confirm our view that the lipoprotein mechanism can be regarded as a dynamic system. During regular episodes following the meals, exogenous fat is, like the vitamins, distributed over all endogenously formed lipoproteins. This transfer process results in the formation of beta-VLDL and contributes to the pathogenesis of FCH and FD.
Demacker
P N
PN
Department of Medicine, University Hospital Nijmegen, The Netherlands. P.demacker@aig.azn.nl
Bredie
S J
SJ
Hectors
M P
MP
Stalenhoef
A F
AF
D002914:Chylomicrons / Q000097:blood*; D004041:Dietary Fats / Q000008:administration & dosage* / Q000378:metabolism; D006801:Humans; D006949:Hyperlipidemias / Q000097:blood*; D008079:Lipoproteins, VLDL / Q000097:blood*; D014801:Vitamin A / Q000008:administration & dosage* / Q000378:metabolism; D014810:Vitamin E / Q000008:administration & dosage* / Q000378:metabolism
D002914:Chylomicrons; D004041:Dietary Fats; D008079:Lipoproteins, VLDL; D014801:Vitamin A; D014810:Vitamin E