Fig. 1

Chemical structure of [¹¹C]SMW139 (a). The binding of [³H]SMW139 was determined by saturation binding assay to human or rat P2X₇R (n = 3). Binding curves of [³H]SMW139 to human; binding affinity K_d = 4.6 ± 0.8 nM (b). Binding curves of [³H]SMW139 to rat P2X₇R; binding affinity K_d = 20.6 ± 1.7 nM (c). In vivo P-glycoprotein blocking with tariquidar. Time activity curve showing the %ID/mL of the baseline scan with [¹¹C]SMW139 in normal wild-type rats (n = 4) (red circle) and after blocking with tariquidar 15 mg/kg (n = 4) (black square) (d). Biodistribution showing the %ID/g (e) and the brain-to-blood ratio (f) of [¹¹C]SMW139 in the brain of normal wild-type rats and after blocking with tariquidar (15 mg/kg). p value was determined by two-tailed t test. SB, specific binding, NS non-specific binding