Table 1

Inhibition of [125I]-labeled CGP64213 binding to chimeric and truncated GABAB receptors by agonists and antagonists

IC50
AgonistAntagonist
GABAAPPAl-BaclofenCGP476561-aCGP64213CGP54626SCH50911
μM
WT R1a22.9  ± 2.42.3  ± 0.525.1  ± 7.810.8  ± 2.20.0023  ± 0.00010.0015  ± 0.00010.38  ± 0.03
WT R1b31.1  ± 4.02.8  ± 0.235.1  ± 4.215.0  ± 2.40.0031  ± 0.00010.002  ± 0.00010.43  ± 0.04
aN1C1.7  ± 0.330.3  ± 0.022.4  ± 0.41.2  ± 0.30.0018  ± 0.00010.0019  ± 0.00030.49  ± 0.05
aN7C2.1  ± 0.10.25  ± 0.012.9  ± 0.31.4  ± 0.090.0021  ± 0.00020.002  ± 0.00120.41  ± 0.03
bN7C1.9  ± 0.120.24  ± 0.0233.1  ± 0.181.6  ± 0.40.002  ± 0.00010.001  ± 0.00020.6  ± 0.05
aN13.0  ± 0.110.29  ± 0.0233.9  ± 0.451.3  ± 0.70.0017  ± 0.000060.003  ± 0.00090.42  ± 0.04
bN13.9  ± 0.450.21  ± 0.0214.7  ± 0.581.4  ± 0.130.0023  ± 0.00030.0009  ± 0.00030.35  ± 0.03
sNa6.8  ± 0.980.36  ± 0.1213.3  ± 2.50.81  ± 0.290.0016  ± 0.00020.0021  ± 0.00040.27  ± 0.05
sNb8.5  ± 0.990.67  ± 0.0918.3  ± 1.22.3  ± 0.220.0011  ± 0.00010.0053  ± 0.0020.35  ± 0.04

Membranes from COS cells transiently transfected with mutant cDNAs were used for radioligand binding. IC50 values were obtained as described (Kaupmann et al., 1997) and are given as means ± S.E. of at least three experiments. Values for WT receptors were included for comparison (Kaupmann et al., 1997)

• APPA, 3-aminopropylphosphinic acid.

• 1-a CGP47656 is a partial agonist (Kaupmann et al., 1997).