(A) Mean (+S.D.) brain time-activity curves of (R)-[11C]verapamil in FVB wild-type mice pretreated i.v. with vehicle solution (at 60 min before PET) or HM30181 (HM, 10 mg/kg at 10, 60 or 120 min before PET or 21 mg/kg at 10 min before PET, n = 4 per group except for 21 mg/kg dose group where n = 2). In (B) mean (+S.D.) brain-to-blood radioactivity concentration ratios at the end of the PET scan (Kb,brain) are shown. For comparison, Kb,brain of (R)-[11C]verapamil in FVB wild-type mice pretreated with vehicle or tariquidar (15 mg/kg) at 120 min before PET is also shown (Kuntner et al., 2010a).