Fig. 1.

Calcium mobilisation assay using aequorin reporter for D1 and InvD1L receptors expressed in Chinese hamster ovary cells (CHO-K1). The light grey bars represent the D1 receptor results, and the dark grey bars represent the InvD1L receptor results. (A) Agonistic activities of various chemicals (10 μmol l⁻¹) on the D1 receptor and InvD1L receptor. The first group of bars represents the full luminescence responses of D1 and InvD1L receptors to 10 μmol l⁻¹ dopamine. (B) Antagonistic activities of various chemicals (10 μmol l⁻¹) on the D1 and InvD1L receptors. The luminescence responses of D1 and InvD1L receptors to 10 μmol l⁻¹ dopamine are shown in the first column, and the responses to 10 μmol l⁻¹ dopamine after pre-incubation with different chemicals (10 μmol l⁻¹) for 15 min are shown in the remaining columns. The bars in the graphs indicate the averages with s.e.m. for three replicates. (C) Structures of the pharmacological discriminators used in this study: dopamine, SKF82958 (D1-specific agonist), fluphenazine (InvD1L-specific antagonist) and SCH23390 (common antagonist). Apo, apomorphine; 6,7-ADTN, (±)-2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide; DA-3, dopamine-3-O-sulfate; DA-4, dopamine-4-O-sulfate; Ace, acepromazine; Clo, clozapine; (+)Bu, (+)-butaclamol; (−)Bu, (−)-butaclamol; Sul, sulpiride; Hal, haloperidol. Asterisks indicate statistical significance in the paired t-test: ***P<0.0001, **P<0.001 and *P<0.01 for differences between D1 and InvD1L.