Hydrogen Peroxide and Platelet Function

Hydrogen peroxide, at concentrations in the micromolar range, can influence platelet function. Although H₂O₂ causes no detectable platelet aggregation at these concentrations, it can aggregate platelets which have been previously exposed to any of several aggregating agents. H₂O₂ can enhance bath aggregation and the subsequent disaggregation of platelets, as initiated by ADP. Preexposure of platelets to H₂O₂ blunts the subsequent response to ADP. Washed platelets are susceptible to H₂O₂. Catalase-treated H₂O₂ has no effect on platelet function. H₂O₂ does not appear to act by altering either the aggregating agent or plasma thrombin generation. These data suggest that minute amounts of H₂O₂, which could theoretically be generated in vivo at sites of platelet plug formation, could play a regulatory role in the dynamics of growth and/or dissipation of the hemostatic plug. The blood granulocyte could participate in hemostasis and thrombosis via H₂O₂ generation.