Figure 2.

Interaction of 11d, 14b, and 5-OH-DPAT with rD2 receptors expressed in HEK-293 cells. Isotherms were obtained in competition experiments with [³H]spiperone as described in the experimental section (see the Supporting Information). The Hill slopes for the curve 11d (n_H = 1.31) and 14b (n_H = 1.43) were higher than monovalent 5-OH-DPAT (n_H = 0.83), indicating a possible cooperative binding interaction with the D2 receptor dimer. Each point is the average ± SEM (vertical bar) of 4–6 independent experiments assayed in triplicate. For K_i values for each curve, see Table 1. The averages shown for 5-OH-DPAT are from a subset of six experiments. The x-axis concentrations are expressed as K_i taking into account the conversion from IC₅₀ as indicated in the methods (see the Supporting Information).