title: Discrimination between forms of vitamin E by humans with and without genetic abnormalities of lipoprotein metabolism.
abstract: To study the mechanisms of discrimination between various forms of vitamin E, four normal subjects, one patient with lipoprotein lipase deficiency, and three patients with abnormal apolipoprotein B-100 production were given an oral dose containing three tocopherols labeled with differing amounts of deuterium (2R,4'R,8'R-alpha-(5,7-(C2H3)2)tocopheryl acetate (d6-RRR-alpha-tocopheryl acetate), 2S,4'R,8'R-alpha-5-(C2H3)tocopheryl acetate (d3-SRR-alpha-tocopheryl acetate), and 2R,4'R,8'R-gamma-(3,4-2H)tocopherol (d2-RRR-gamma-tocopherol). The tocopherol contents of plasma, red cells, and lipoproteins were measured up to 76 h after the dose. In normal subjects all three tocopherols were absorbed and secreted in chylomicrons with equal efficiencies. Both d2-gamma- and d3-SRR-alpha-tocopherols peaked at similar concentrations in the other lipoprotein fractions, then decreased similarly, but 2-4 times more rapidly than did d6-RRR-alpha-tocopherol. A lipoprotein lipase-deficient patient and a patient with prolonged production of chylomicrons with absent apolipoprotein B-100 also demonstrated the lack of discrimination between tocopherols during absorption. Despite abnormal apolipoprotein B-100 production in two patients, the "VLDL" was preferentially enriched in d6-RRR-alpha-tocopherol. Our results show that there is no discrimination between the three tocopherols during absorption and secretion in chylomicrons, but subsequently there is a preferential enrichment of very low density lipoprotein (VLDL) with RRR-alpha-tocopherol. Catabolism of this VLDL results in the maintenance of plasma RRR-alpha-tocopherol concentrations.
authors.affiliation: NYU School of Medicine, NY 10016.
authors.forename: M G
authors.initials: MG
authors.lastname: Traber
authors.forename: G W
authors.initials: GW
authors.lastname: Burton
authors.forename: L
authors.initials: L
authors.lastname: Hughes
authors.forename: K U
authors.initials: KU
authors.lastname: Ingold
authors.forename: H
authors.initials: H
authors.lastname: Hidaka
authors.forename: M
authors.initials: M
authors.lastname: Malloy
authors.forename: J
authors.initials: J
authors.lastname: Kane
authors.forename: J
authors.initials: J
authors.lastname: Hyams
authors.forename: H J
authors.initials: HJ
authors.lastname: Kayden
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D002914:Chylomicrons / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D006801:Humans; D008072:Hyperlipoproteinemia Type I / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000378:metabolism; D008297:Male; D014810:Vitamin E / Q000378:metabolism*
chemical_list: D002914:Chylomicrons; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D014810:Vitamin E