TABLE 4.

Functional properties of catechol agonists for wild-type human D₁ and TM5 serine mutant receptors

Data represent means ± S.E.M. of potency (EC₅₀) and intrinsic activity (normalized to percentage of 100 μM dopamine) in response to D₁ receptor-stimulated cAMP accumulation (n ≥ 3). Statistical significance was determined from pEC₅₀ values. The dopamine EC₅₀ values are taken from Table 2.

Ligand	hD1 WT		S198A		S199A		S202A
	EC50	IA	EC50	IA	EC50	IA	EC50	IA
	nM	% DA	nM	% DA	nM	% DA	nM	% DA
DAa	22 ± 3.4	100	7800 ± 570**	100	2800 ± 400**	100	12,000 ± 370**	100
Cyclohexyl isochroman	1.6 ± 0.1	114 ± 4.2	430 ± 88**	157 ± 5.7	75 ± 12**	119 ± 6.9	570 ± 74**	231 ± 14
Cyclohexyl carbocyclic	120 ± 7.4	108 ± 5.2	14,000 ± 1500**	149 ± 15	7900 ± 730**	132 ± 6.7	17,000 ± 1700**	175 ± 9.8
Cyclohexyl chroman	820 ± 110	125 ± 2.9	49,000 ± 7500**	76 ± 5.5	12,000 ± 1900**	124 ± 5.3	34,000 ± 3900**	48 ± 1.1
Apomorphine	70 ± 9.4	110 ± 6.1	14,000 ± 810**	78 ± 4.2	1200 ± 310**	124 ± 6.4	14,000 ± 2200**	108 ± 8.1
Dinapsoline	6.3 ± 1.0	113 ± 3.6	1600 ± 130**	132 ± 9.7	190 ± 34**	132 ± 10	3000 ± 400**	145 ± 5.9
Dihydrexidine	5.2 ± 0.8	104 ± 2.9	940 ± 106**	132 ± 10	240 ± 18**	109 ± 12	750 ± 140**	101 ± 3.3
Doxanthrine	6.4 ± 1.2	101 ± 3.4	470 ± 80**	125 ± 16	240 ± 49**	101 ± 4.2	240 ± 33**	95 ± 4.5
SKF 38393	38 ± 3.1	92 ± 3.5	2600 ± 340**	58 ± 3.3	1000 ± 190**	51 ± 1.7	180 ± 6.7**	62 ± 3.5
SKF 81297	2.1 ± 0.4	107 ± 5.9	480 ± 29**	139 ± 5.4	64 ± 9.2**	122 ± 1.9	7.6 ± 1.2**	223 ± 16
SKF 82958	2.6 ± 0.9	115 ± 1.3	200 ± 35**	137 ± 2.8	63 ± 3.4**	123 ± 7.4	11 ± 2.9**	211 ± 8.8
SKF 83959	1.8 ± 0.2	82 ± 3.5	130 ± 4.3**	90 ± 4.1	25 ± 0.5**	74 ± 6.6	6.5 ± 2.4**	103 ± 4.9

^* Significantly different from wild-type (p < 0.05).

^** Significantly different from wild-type (p < 0.01).