TABLE 1

Equilibrium and kinetic binding experiments of [³H]nemonapride in the presence and absence of a fixed concentration of SB269,652 in stable transfected CHO-D₂ and CHO-D₃ cells

All values are the mean ± S.E.M. of three experiments, each of which was performed in triplicate. The concentration of [³H]nemonapride in association binding experiments was 0.65 nM. Data are the mean ± S.E.M. of two experiments each performed in triplicate. The K_off values reported in the control columns for D₂ and D₃ receptors are the averages of values specified in the text for dissociations performed in the presence of haloperidol or sulpiride.

	Saturation Binding				Binding Kinetics
	Parameter	Control	SB269,652		Parameter	Control	SB269,652		Parameter	Control	SB269,652 (10 μM)
	Parameter	Control	10 nM	10 μM	Parameter	Control	50 nM	10 μM	Parameter	Control	SB269,652 (10 μM)
CHO-D₂	K_d (nM)	0.195 ± 0.014		0.196 ± 0.013	K_ob (min⁻¹)	0.153 ± 0.007		0.054 ± 0.008	K_off (min⁻¹)	0.0225	0.007 ± 0.0003
	B_max (fmol/mg protein)	3218 ± 77.8		2271 ± 51.3	K_on (min⁻¹ · nM⁻¹)	0.2008		0.0723	K_off /K_on (nM)	0.112	0.097
CHO-D₃	K_d (nM)	0.421 ± 0.035	0.409 ± 0.034	0.447 ± 0.074	K_ob (min⁻¹)	0.295 ± 0.019	0.025 ± 0.003	0.019 ± 0.002	K_off (min⁻¹)	0.0615	0.007 ± 0.0003
	B_max (fmol/mg protein)	4932 ± 173	3395 ± 117	564 ± 40.3	K_on (min⁻¹ · nM⁻¹)	0.3594		0.0185	K_off /K_on (nM)	0.171	0.378