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Am J Clin Nutr. 2003 Mar;77(3):700-6.

Mixed tocopherols inhibit platelet aggregation in humans: potential mechanisms.

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1
Department of Surgical Sciences, Section of Forensic Medicine, University of Uppsala, Sweden.

Abstract

BACKGROUND:

Epidemiologic studies have shown an inverse correlation between acute coronary events and high intake of dietary vitamin E. Recent clinical studies, however, failed to show any beneficial effects of alpha-tocopherol on cardiovascular events. Absence of tocopherols other than alpha-tocopherol in the clinical studies may account for the conflicting results.

OBJECTIVE:

This study compared the effect of a mixed tocopherol preparation rich in gamma-tocopherol with that of alpha-tocopherol on platelet aggregation in humans and addressed the potential mechanisms of the effect.

DESIGN:

Forty-six subjects were randomly divided into 3 groups: alpha-tocopherol, mixed tocopherols, and control. ADP and phorbol 12-myristate 13-acetate-induced platelet aggregation, nitric oxide (NO) release, activation of endothelial constitutive nitric-oxide synthase (ecNOS; EC 1.14.13.39) and of protein kinase C (PKC), and ecNOS, superoxide dismutase (SOD; EC 1.15.1.1), and PKC protein content in platelets were measured before and after 8 wk of administration of tocopherols.

RESULTS:

ADP-induced platelet aggregation decreased significantly in the mixed tocopherol group but not in the alpha-tocopherol and control groups. NO release, ecNOS activation, and SOD protein content in platelets increased in the tocopherol-treated groups. PKC activation in platelets was markedly decreased in the tocopherol-treated groups. Mixed tocopherols were more potent than alpha-tocopherol alone in modulating NO release and ecNOS activation but not SOD protein content or PKC activation.

CONCLUSIONS:

Mixed tocopherols were more potent in preventing platelet aggregation than was alpha-tocopherol alone. Effects of mixed tocopherols were associated with increased NO release, ecNOS activation, and SOD protein content in platelets, which may contribute to the effect on platelet aggregation.

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PMID:
12600864
[Indexed for MEDLINE]
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