The effect of triflusal on human platelet aggregation and secretion: the role of nitric oxide

INTRODUCTION AND AIMS: The thrombotic process is a multicellular phenomenon in which not only platelets are involved but also neutrophils are involved. Recent in vitro studies performed in our laboratory have demonstrated that triflusal reduced platelet aggregation by stimulating nitric oxide (NO) production by neutrophils. The aim of the present study was to evaluate whether the in vivo treatment with triflusal could also modify the ability of neutrophils to produce NO. Furthermore, the role of NO released by neutrophils on platelet aggregation and secretion was also tested. METHODS: The study was performed in 12 healthy volunteers of 32 +/- 6 years of age. The volunteers were treated with triflusal (600 mg/day) for 5 days and platelets and neutrophils were isolated before and after treatment. The ability of neutrophils to produce NO and the capacity of inhibiting platelet aggregation and secretion of transforming growth factor-beta (TGF-beta) were assessed. RESULTS: After the treatment with triflusal we obtained the following results: a) an increase in NO production by neutrophils; b) potentiation of the inhibition of platelet aggregation by neutrophils, an effect that was reverted by incubating neutrophils with an L-arginine antagonist, L-NAME, and c) the presence of neutrophils reduced the release of TGF-beta by platelets measured as index of platelet secretion by a NO-independent mechanism. CONCLUSIONS: Triflusal (600 mg/day/5 days) stimulated NO production by neutrophils. After the treatment with triflusal, neutrophils inhibited both platelet aggregation and secretion. The antiaggregating effect of neutrophils was an NO-dependent mechanism while the inhibition of platelet secretion mediated by neutrophils after the treatment with triflusal was an NO-independent mechanism.