The aim of this study was to investigate the effects of a micronized purified flavonoid fraction (MPFF) on in vivo rat platelet functions. Platelet aggregation and disaggregation were evaluated by a noninvasive, automated isotope monitoring system (AimsPlus). Indium-labeled platelets were injected into anesthetized rats and stimulated by adenosine diphosphate (ADP) (10 μg/kg, i.v.) or collagen (50 μg/ kg, i.v.). Fibrinogen binding to ex vivo ADP-activated platelets was determined by flow cytometry. MPFF (100 mg/kg, p.o.) significantly reduced ADP-induced platelet aggregation ( p<0.05) and increased platelet disaggregation ( p<0.05) compared with controls. Moreover, MPFF inhibited collagen-induced platelet aggregation ( p<0.001) and increased platelet disaggregation ( p<0.01). In addition, fibrinogen binding to 2.5 or 5 μM ADP-stimulated platelets also was reduced significantly ( p<0.05 and 0.01, respectively). These results show that MPFF inhibits in vivo rat platelet functions.
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