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Mol Nutr Food Res. 2012 Jun;56(6):912-22. doi: 10.1002/mnfr.201100751.

Vitamin E decreases extra-hepatic menaquinone-4 concentrations in rats fed menadione or phylloquinone.

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  • 1School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA.

Erratum in

  • Mol Nutr Food Res. 2013 Jun;57(6):1115.

Abstract

SCOPE:

The mechanism for increased bleeding and decreased vitamin K status accompanying vitamin E supplementation is unknown. We hypothesized that elevated hepatic α-tocopherol (α-T) concentrations may stimulate vitamin K metabolism and excretion. Furthermore, α-T may interfere with the side chain removal of phylloquinone (PK) to form menadione (MN) as an intermediate for synthesis of tissue-specific menaquinone-4 (MK-4).

METHODS AND RESULTS:

In order to investigate these hypotheses, rats were fed phylloquinone (PK) or menadione (MN) containing diets (2 μmol/kg) for 2.5 weeks. From day 10, rats were given daily subcutaneous injections of either α-T (100 mg/kg) or vehicle and were sacrificed 24 h after the seventh injection. Irrespective of diet, α-T injections decreased MK-4 concentrations in brain, lung, kidney, and heart; and PK in lung. These decreases were not accompanied by increased excretion of urinary 5C- or 7C-aglycone vitamin K metabolites, however, the urinary α-T metabolite (α-CEHC) increased ≥ 100-fold. Moreover, α-T increases were accompanied by downregulation of hepatic cytochrome P450 expression and modified expression of tissue ATP-binding cassette transporters.

CONCLUSION:

Thus, in rats, high tissue α-T depleted tissue MK-4 without significantly increasing urinary vitamin K metabolite excretion. Changes in tissue MK-4 and PK levels may be a result of altered regulation of transporters.

© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PMID:
22707266
[PubMed - indexed for MEDLINE]
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