TABLE 1.

Agonist binding affinities of the dopamine D5 receptor expressed alone or coexpressed with the dopamine D2 receptor

Competition binding experiments using [³H]SCH 23390 were performed in membranes from cells stably transfected with the D5 receptor alone or cotransfected with the D2 receptor. The data represent the means ± S.E.M of six experiments, each performed in duplicate.

	D5R			D5R + D2R
	Fraction	KH	KL	Fraction	KH	KL
		nM	nM		nM	nM
Dopamine	0.317 ± 0.072	132.4 ± 72.0	3936 ± 997.2	0.338 ± 0.048	171.9 ± 69.1	6407 ± 1396
SKF 81297	0.217 ± 0.041	8.1 ± 4.1	33.9 ± 8.5	0.198 ± 0.033	8.2 ± 2.9	20.4 ± 3.5

KH, high-affinity constant; KL, low-affinity constant.