Transport of deuterium-labeled tocopherols during pregnancy.
With use of deuterium-labeled isotopes of RRR- and all-rac-alpha-tocopheryl acetate, the transport of vitamin E in pregnancy was evaluated to determine whether the placenta discriminates between these compounds. Fifteen pregnant subjects were recruited 5 d before delivery to receive 15, 30, 75, 150, or 300 mg vitamin E/d in capsules containing d3-RRR-alpha-tocopheryl acetate and d6-all-rac-alpha-tocopheryl acetate (1:1, by wt). Maternal blood was obtained before dosing, at hospital admission, and at parturition. Cord blood samples were obtained at parturition. Deuterium-labeled and unlabeled tocopherol contents were determined by gas chromatography-mass spectrometry in plasma and lipoproteins (chylomicrons, VLDL, LDL, and HDL). Maternal plasma and lipoproteins obtained at delivery had higher concentrations of d3-RRR-alpha-tocopherol than d6-all-rac-alpha-tocopherol regardless of the vitamin E dose administered (P < 0.05). Cord plasma at delivery also had higher concentrations of d3-RRR-alpha-tocopherol than d6-all-rac-alpha-tocopherol in plasma irrespective of the dose administered (P < 0.05). In lipoproteins isolated from cord blood, tocopherol concentrations were greatest in the HDL fraction (P < 0.05), whereas in maternal blood they were greatest in the LDL fraction (P < 0.05). We conclude that the placental-fetal unit, the fetal liver, or both further discriminate between RRR- and all-rac-alpha-tocopherol.
Acuff
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RV
Eastman Center for Nutrition Research, James H Quillen College of Medicine, East Tennessee State University, Johnson City 37614-0410, USA. acuffr@access.etsu.edu
Dunworth
R G
RG
Webb
L W
LW
Lane
J R
JR
D000328:Adult; D003903:Deuterium / Q000378:metabolism*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008074:Lipoproteins / Q000097:blood; D008431:Maternal-Fetal Exchange; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy / Q000378:metabolism*; D011263:Pregnancy Trimester, Third; D014810:Vitamin E / Q000493:pharmacokinetics*
D008074:Lipoproteins; D014810:Vitamin E; D003903:Deuterium