TABLE 1

Summary of pharmacological properties of structurally dissimilar D₁ agonists

Intrinsic activity data are expressed relative to dopamine. See Materials and Methods for details of analysis.

Ligand	Affinity				Adenylate Cyclase		Internalization Intrinsic Activity
Ligand	K_0.5	n_H	K_D(High) (nM) R_High (%)	K_D(Low) (nM) R_Low (%)	EC₅₀	Intrinsic Activity	Internalization Intrinsic Activity
	nM				nM
Dopamine	300 ± 120	-0.45 ± 0.04	19 ± 0.30	2100 ± 38	23 ± 18
			46 ± 3.0	44 ± 3.0
Apomorphine	240 ± 76	-0.85 ± 0.04	0.49 ± 0.03	240 ± 2.0	37 ± 3	86 ± 4	0.0
			7.6 ± 2.0	92 ± 2.0
Dinapsoline	48 ± 5.0	-0.46 ± 0.05	1.4 ± 0.03	140 ± 3.6	4.0 ± 3.0	100 ± 18	106 ± 3
			43 ± 6.0	57 ± 6.0
Dinoxyline	16 ± 9.3	-0.40 ± 0.05	0.12 ± 0.01	30 ± 0.46	4.0 ± 3.0	102 ± 14	118 ± 2
			44 ± 4.0	56 ± 4.0
Dihydrexidine	71 ± 8.5	-0.63 ± 0.09	0.06 ± 0.01	25 ± 0.20	15 ± 0.5	96 ± 8	110 ± 5
			21 ± 3.0	79 ± 3.0
A86929	7.8 ± 1.5	-0.68 ± 0.06	2.5 ± 0.03	110 ± 4.2	2.3 ± 0.5	91 ± 15	108 ± 3
			68 ± 7.0	32 ± 7.0
SKF38393	240 ± 140	-0.63 ± 0.05	14 ± 0.39	370 ± 11	13 ± 1.0	67 ± 1	0.0
			48 ± 11	52 ± 11
SKF77434	52 ± 2	-0.75 ± 0.07	0.79 ± 0.04	45 ± 0.63	11 ± 2.0	46 ± 12	0.0
			18 ± 6.0	82 ± 6.0
SKF83959	2.7 ± 0.7	-0.94 ± 0.10	N.A.	N.A.	5.6 ± 0.6	42 ± 3	0.0
SKF82957	2.5 ± 0.3	-1.00 ± 0.09	N.A.	N.A.	0.8 ± 0.6	55 ± 9	0.0
SKF81297	10 ± 1	-0.654 ± 0.05	1.8 ± 0.12	36 ± 0.59	2.6 ± 1.2	89 ± 11	105 ± 3
			42 ± 8.0	58 ± 8.0
SKF82958	6.5 ± 0.2	-0.73 ± 0.05	1.2 ± 0.03	14 ± 0.31	3.0 ± 2.6	86 ± 12	105 ± 3
			46 ± 14	54 ± 14
A77636	3.8 ± 1.3	-1.01 ± 0.07	N.A.	N.A.	5.3 ± 2.0	99 ± 7	118 ± 2
A68930	2.4 ± 0.2	-0.78 ± 0.05	0.90 ± 0.01	18 ± 0.49	0.3 ± 0.1	97 ± 3	124 ± 2
			73 ± 0.07	27 ± 0.02