title: Vitamin E. An inhibitor of the platelet release reaction.
abstract: Formation of lipid peroxides rises sharply when platelets undergo the release reaction. In this study the in vitro effect of vitamin E on platelet aggregation was investigated. alpha-Tocopherol, an anitoxidant of known inhibitory action on lipid peroxidation, was added to platelet suspensions in concentrations up to 1.5 mM. A dose-dependent reduction in platelet aggregation was observed, with complete inhibition of the secondary wave of aggregation at greater than or equal to 0.9 mM alpha-tocopherol. The inhibitory effect of alpha-tocopherol on the platelet release reaction was further documented by the decrease in aggregation-induced release of [14C]5-hydroxytryptamine from prelabeled platelets and by the reduction of N-acetylglucosaminidase activity released into the medium. The sharp rise in lipid peroxides normally associated with platelet aggregation was markedly reduced by alpha-tocopherol and also by acetylsalicylic acid, a known inhibitor of the platelet release reaction. In vivo studies examined the effect of oral vitamin E administration (1,200-2,400 IU daily) on plasma and platelet levels of alpha-tocopherol. Up to 1,800 IU daily, increasing dosages of vitamin E resulted in increasing concentrations of alpha-tocopherol in plasma and platelets, but intake of vitamin E in excess of this dosage failed to show any further increase in plasma or platelet levels.
mesh_terms: D000118:Acetylglucosaminidase / Q000378:metabolism; D000328:Adult; D001792:Blood Platelets / Q000201:enzymology / Q000378:metabolism; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D050356:Lipid Metabolism; D008297:Male; D008875:Middle Aged; D010545:Peroxides / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism; D014810:Vitamin E / Q000378:metabolism / Q000494:pharmacology*; D014811:Vitamin E Deficiency / Q000378:metabolism
chemical_list: D010545:Peroxides; D014810:Vitamin E; D012701:Serotonin; D000118:Acetylglucosaminidase