title: Antioxidants change platelet responses to various stimulating events.
abstract: The role of platelets in hemostasis may be influenced by alteration of the platelet redox state-the presence of antioxidants and the formation of reactive oxygen and nitrogen species. We investigated the effects of two antioxidants, resveratrol and trolox, on platelet activation. Trolox and resveratrol inhibited aggregation of washed platelets and platelet-rich plasma activated by ADP, collagen, and thrombin receptor-activating peptide. Resveratrol was a more effective agent in reducing platelet static and dynamic adhesion in comparison with trolox. The antioxidant capacity of resveratrol was, however, the same as that of trolox. After incubation of platelets with antioxidants, the resveratrol intraplatelet concentration was about five times lower than the intracellular concentration of trolox. Although both antioxidants comparably lowered hydroxyl radical and malondialdehyde production in platelets stimulated with collagen, TxB(2) levels were decreased by resveratrol much more effectively than by trolox. Cyclooxygenase 1 was inhibited by resveratrol and not by trolox. Our data indicate that antioxidants, apart from nonspecific redox or radical-quenching mechanisms, inhibit platelet activation also by specific interaction with target proteins. The results also show the importance of studying platelet activation under conditions of real blood flow in contact with reactive surfaces, e.g., using dynamic adhesion experiments.
authors.affiliation: Institute of Hematology and Blood Transfusion, U Nemocnice 1, 128 00 Prague 2, Czech Republic.
authors.forename: Alzbeta
authors.initials: A
authors.lastname: Sobotková
authors.forename: Leona
authors.initials: L
authors.lastname: Másová-Chrastinová
authors.forename: Jirí
authors.initials: J
authors.lastname: Suttnar
authors.forename: Jana
authors.initials: J
authors.lastname: Stikarová
authors.forename: Pavel
authors.initials: P
authors.lastname: Májek
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Reicheltová
authors.forename: Roman
authors.initials: R
authors.lastname: Kotlín
authors.forename: John W
authors.initials: JW
authors.lastname: Weisel
authors.forename: Martin
authors.initials: M
authors.lastname: Malý
authors.forename: Jan E
authors.initials: JE
authors.lastname: Dyr
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002839:Chromans / Q000494:pharmacology*; D003094:Collagen / Q000494:pharmacology; D051545:Cyclooxygenase 1 / Q000378:metabolism; D006487:Hemostasis / Q000187:drug effects; D006801:Humans; D008315:Malondialdehyde / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects* / Q000502:physiology; D000077185:Resveratrol; D013267:Stilbenes / Q000494:pharmacology*; D013929:Thromboxane B2 / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002839:Chromans; D013267:Stilbenes; D008315:Malondialdehyde; D013929:Thromboxane B2; D003094:Collagen; D051545:Cyclooxygenase 1; D000077185:Resveratrol; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid