Table 2

Affinity of D1, D2, and chimeric dopamine receptors for agonists

DrugKi
D1D2[1-4,7]D2[1-5,7]D2
6,7-ADTN15,000  (12,000–20,000)41  (38–46)500  (310–820)600  (370–970)
Apomorphine430  (400–470)2.5  (2.1–3.1)110  (87–130)530  (410–680)
NPA620  (430–880)1.5  (1.1–2.0)14  (12–17)26  (18–39)
Dihydrexidine (μm)1.2  (1.0–1.4)0.30  (0.29–0.31)4.8  (3.4–6.7)1.7  (1.5–1.9)
Dopamine (μm)31  (21–44)0.52  (0.39–0.70)20  (14–29)13  (11–15)
Bromocriptine1,400  (900–1,900)6.1  (4.8–7.8)9.5  (9.3–9.7)2.2  (2.1–2.4)
Lisuride77  (63–94)0.4  (0.2–0.7)1.4  (0.9–2.3)0.70  (0.59–0.82)
Pergolide2,000  (1,500–2,800)25  (19–34)29  (27–31)85  (67–110)
Fenoldopam85  (59–120)320  (210–460)520  (400–690)1,300  (900–1,800)
Quinpirole (μm)100  (70–120)13  (9–19)20  (17–24)10  (10–14)
6-Chloro-PB58  (43–79)800  (680–950)850  (400–1400)4,800  (3,600–6,500)
Chloro-APB36  (33–38)110  (110–120)1,900  (1,700–2,000)1,700  (1,600–1,800)
SKF38393 (μm)0.53  (0.34–0.84)10  (0.8–1.4)20  (11–36)21  (18–24)

Ki values for inhibition by the indicated agonists of the binding of [3H]spiperone to chimeric and D2 receptors and the binding of [3H]SCH23390 to D1 receptors determined as described in Experimental Procedures. All experiments were carried out in the presence of 200 μm GTP. Affinity values (nm except where indicated) represent geometric mean values from three or more independent experiments with the limits defined by the asymmetrical standard error given in parentheses.