Table 4

Stimulation of [³⁵S]GTPγS binding by dopaminergic ligands at hD₂ and hD₃ receptors

Agonist	hD₂		hD₃		EC₅₀Ratio hD₂/hD₃
Agonist	pEC₅₀	EC₅₀	E_MAX	nH	EC₅₀Ratio hD₂/hD₃	pEC₅₀	EC₅₀	E_MAX	nH
		nM	%			nM	%
Dopamine	6.45 ± 0.03	350	103.5 ± 4.9	1.10 ± 0.10	8.00 ± 0.07	10	100.1 ± 3.2	0.82 ± 0.07	35
(+)-7-OH-DPAT	7.35 ± 0.11	44.6	64.3 ± 2.8	0.86 ± 0.10	9.24 ± 0.26	0.58	55.4 ± 4.2	1.27 ± 0.24	77
PD 128,907	6.33 ± 0.10	467	116 ± 3.8	0.73 ± 0.18	8.91 ± 0.12	1.22	63.6 ± 2.8	1.21 ± 0.31	382
S 14297	7.31 ± 0.08	48.6	20.6 ± 1.9	1.53 ± 1.11	n.c.	n.c.	0	n.c.	n.c.

Agonist efficacies were determined by [³⁵S]GTPγS binding. Results are means ± S.E. of mean of at least three independent experiments. EC₅₀ values were calculated from mean pEC₅₀ values. Haloperidol and GR 218,231 did not induce any alteration of [³⁵S]GTPγS binding to either hD₂ or hD₃ membranes. S 14297 did not alter [³⁵S]GTPγS binding to hD₃ membranes.

n.c., not computable.