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. 1998 Dec 8;95(25):14991–14996. doi: 10.1073/pnas.95.25.14991

Table 1.

Ligand-binding affinities at cloned human GABAB receptors

Ligand GABABR1a
GABABR1b
IC50, μM Hill coeff. nH IC50, μM Hill coeff. nH
Agonists
 GABA 30.5  ± 3.4 0.82  ± 0.02 30.9  ± 2.9 1.03  ± 0.08
 APPA 2.5  ± 0.6 0.82  ± 0.07 2.5  ± 0.4 0.87  ± 0.02
 Baclofen 31.8  ± 2.3 0.85  ± 0.06 30.1  ± 4.0 0.89  ± 0.14
 CGP47656 14.8  ± 0.9 0.73  ± 0.03 13.9  ± 1.4 0.69  ± 0.12
Antagonists
 CGP56999A 0.0007  ± 0.0001 1.33  ± 0.12 0.0006  ± 0.0002 1.30  ± 0.27
 CGP62349 0.0011  ± 0.0002 0.85  ± 0.09 0.0007  ± 0.0001 0.80  ± 0.13
 CGP64213 0.0023  ± 0.0003 1.00  ± 0.09 0.0019  ± 0.0004 0.97  ± 0.06
 CGP54626A 0.0019  ± 0.0004 1.06  ± 0.06 0.0014  ± 0.0004 0.96  ± 0.13
 CGP71872 0.0030  ± 0.0003 1.00  ± 0.12 0.0026  ± 0.0006 0.93  ± 0.07
 CGP35348 20.1  ± 2.5 0.82  ± 0.09 15.8  ± 3.3 0.72  ± 0.03
 2-OH-saclofen 67.9  ± 4.4 0.90  ± 0.11 49.1  ± 11.2 0.76  ± 0.04
 Saclofen 310  ± 57 0.69  ± 0.16 299  ± 59 0.53  ± 0.02
 SCH50911 0.35  ± 0.02 0.86  ± 0.15 0.35  ± 0.05 0.93  ± 0.04

Inhibition of [125I]CGP64213 binding to recombinant human GABABRs by GABAB agonists and antagonists. Membranes from transiently transfected COS-1 cells (hR1a) and stably transfected CHO-K1 (hR1b) were used. IC50 values and Hill coefficients were fitted by using nonlinear regression (prism 2.0, Graph Pad Software, Sand Diego). Values are means ± SEM of three independent experiments. APPA, 3-aminopropylphosphinic acid.