title: Hyperlipidemic subjects have reduced uptake of newly absorbed vitamin E into their plasma lipoproteins, erythrocytes, platelets, and lymphocytes, as studied by deuterium-labeled alpha-tocopherol biokinetics.
abstract: Vitamin E homeostasis in hyperlipidemia is poorly understood. The biokinetics of deuterated alpha-tocopherol (alpha-T) in blood components was investigated in normolipidemic (N; total cholesterol < 5.5 mmol/L and triglycerides < 1.5 mmol/L, n = 9), hypercholesterolemic (HC; total cholesterol > 6.5 mmol/L and triglycerides < 1.5 mmol/L, n = 10), and combined hypercholesterolemic and hypertriglyceridemic (HCT; total cholesterol > 6.5 mmol/L and triglycerides > 2.5 mmol/L, n = 6) subjects. Subjects ingested 150 mg hexadeuterated RRR-alpha-tocopheryl acetate, and blood was collected up to 48 h after ingestion. Labeled alpha-T was measured in plasma, lipoproteins, erythrocytes, platelets, and lymphocytes by liquid chromatography/mass spectroscopy. In plasma, HC had an earlier time of maximum concentration (6 h) compared with N and HCT (12 h) (P < 0.05). HCT had a lower uptake of labeled alpha-T (P < 0.005) and a longer half-life (P < 0.05). In chylomicrons, the maximum labeled alpha-T concentration was higher in HC compared with N and HCT (P < 0.00005); however, HCT had a lower uptake of labeled alpha-T in LDL. In all groups, the lowest density LDL subfraction contained more labeled alpha-T than denser subfractions (P < 0.05). In platelets, lymphocytes, and erythrocytes, the areas under the labeled alpha-T concentration vs. time curves were in the order N > HC > HCT. In lymphocytes, differences in labeled alpha-T were found at 6 and 48 h (P < 0.05). These data demonstrate that there are differences in the uptake of newly absorbed alpha-T into blood components in hyperlipidemia. Because these blood components are functionally affected by vitamin E, reduced uptake of alpha-T may be relevant to the pathogenesis of atherosclerosis.
authors.affiliation: Centre for Nutrition and Food Safety, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
authors.forename: Wendy L
authors.initials: WL
authors.lastname: Hall
authors.forename: Yvonne M
authors.initials: YM
authors.lastname: Jeanes
authors.forename: John K
authors.initials: JK
authors.lastname: Lodge
mesh_terms: D000328:Adult; D001692:Biological Transport; D001792:Blood Platelets / Q000378:metabolism*; D003903:Deuterium; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000378:metabolism*; D006949:Hyperlipidemias / Q000097:blood / Q000503:physiopathology*; D007408:Intestinal Absorption / Q000502:physiology*; D007700:Kinetics; D008074:Lipoproteins / Q000097:blood*; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011865:Radioisotope Dilution Technique; D012016:Reference Values; D024502:alpha-Tocopherol / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D008074:Lipoproteins; D003903:Deuterium; D024502:alpha-Tocopherol