Membranes were incubated simultaneously with [³H]WEB-2086 (20 nM) and the compounds for 90 min at 25°C. EachK _i ^app value represents the mean ± S.E. of K _i values obtained from three separate experiments, each one involving eight different concentrations of the drug assayed in duplicate. The K _D value used to calculate K _i was 10 nM.