NF449 (octasodium)

NF449 octasodium is a highly potent P2X₁ receptor antagonist, with IC₅₀s of 0.28, 0.69, and 120 nM for rP2X₁, rP2X₁₊₅, P2X₂₊₃, respectively. NF449 octasodium is a G_sα-selective G Protein antagonist. NF449 octasodium suppresses the rate of GTP[γS] binding to G_sα-s, inhibits the stimulation of adenylyl cyclase activity, and blocks the coupling of β-adrenergic receptors to G_s^[1][2]. In Vitro: NF449 suppressed the rate of GTP[γS] binding to rG_sα-s while barely affecting binding to rG_iα-1 (IC₅₀=140 nM), inhibits stimulation of adenylyl cyclase activity in S49 cyc− membranes (deficient in endogenous Gsα) by exogenously added Gsα-s, and blocks the coupling of β-adrenergic receptors to G_s (EC₅₀=7.9 μM)^[2]. In Vivo: At a dose of 10 mg/kg, NF449 inhibits the ex vivo aggregation triggered by 5 g/ml collagen in WT mouse platelets without affecting that induced by 5 μM ADP. At a higher dose (50 mg/kg), NF449 inhibits ex vivo platelet aggregation in response to not only 10 g/ml collagen but also 5 M ADP, indicating nonselective inhibition of the P2Y1 and/or P2Y12 receptor^[3].