Antiplatelet Activity of J78 (2-Chloro-3-[2′-bromo, 4′-fluoro-phenyl]-amino-8-hydroxy-1,4-naphthoquinone), an Antithrombotic Agent, Is Mediated by Thromboxane (TX) A₂ Receptor Blockade with TXA₂ Synthase Inhibition and Suppression of Cytosolic Ca²+ Mobilization

We previously reported that J78 (2-chloro-3-[2'-bromo, 4'-fluoro-phenyl]-amino-8-hydroxy-1,4-naphthoquinone), a newly synthesized 1,4-naphthoquinone derivative, exhibited a potent antithrombotic effect, which might be due to antiplatelet rather than anticoagulation activity. In the present study, possible anti-platelet mechanism of J78 was investigated. J78 concentration-dependently inhibited rabbit platelet aggregation induced by collagen (10...