Figure 3.

Curve-shift assays indicate that ML321 behaves in a competitive manner with dopamine at the D2R. D2R-mediated β-arrestin recruitment assays (A) or cAMP inhibition assays (LANCE) (B) were conducted by stimulating the receptor with the indicated concentrations of dopamine with or without various concentrations of ML321 as described in the Methods. For the cAMP assay, the cells were incubated with 10 μM forskolin to stimulate cAMP production. Data are expressed as a percentage of the maximum dopamine response seen in the absence of ML321 (% control) and represent the mean ± SEM of at least three independent experiments each performed in triplicate. Insets show Schild analyses of the data from which mean K_B values [95% C.I.] were derived. (A) ML321 K_B = 103 nM [76.7–127] (n = 3), (B) ML321 K_B = 8.36 nM [3.5–16.5] (n = 3).