Biological properties of a specific Gαq/11 inhibitor, YM-254890, on platelet functions and thrombus formation under high-shear stress

1 The effects of YM-254890, a specific Gαq/11 inhibitor, on platelet functions, thrombus formation under high-shear rate condition and femoral artery thrombosis in cynomolgus monkeys were investigated. 2 YM-254890 concentration dependently inhibited ADP-induced intracellular Ca2+ elevation, with an IC50 value of 0.92±0.28 μM. 3 P-selectin expression induced by ADP or thrombin receptor agonist peptide (TRAP) was strongly inhibited by YM-254890, with IC50 values of 0.51±0.02 and 0.16±0.08 μM, respectively. 4 YM-254890 had no effect on the binding of fibrinogen to purified GPIIb/IIIa, but strongly inhibited binding to TRAP-stimulated washed platelets. 5 YM-254890 completely inhibited platelet shape change induced by ADP, but not that induced by collagen, TRAP, arachidonic acid, U46619 or A23187. 6 YM-254890 attenuated ADP-, collagen-, TRAP-, arachidonic acid- and U46619-induced platelet aggregation with IC50 values of <1 μM, whereas it had no effect on phorbol 12-myristate 13-acetate-, ristocetin-, thapsigargin- or A23187-induced platelet aggregation. 7 High-shear stress-induced platelet aggregation and platelet-rich thrombus formation on a collagen surface under high-shear flow conditions were concentration dependently inhibited by YM-254890. 8 The antithrombotic effect of YM-254890 was evaluated in a model of cyclic flow reductions in the femoral artery of cynomolgus monkeys. The intravenous bolus injection of YM-254890 dose dependently inhibited recurrent thrombosis without affecting systemic blood pressure or prolonging template bleeding time. 9 YM-254890 is a useful tool for investigating Gαq/11-coupled receptor signaling and the physiological roles of Gαq/11. British Journal of Pharmacology (2006) 148, 61–69. doi:10.1038/sj.bjp.0706711