Table 1. Pharmacological Evaluation of Fluorescent and Biotinylated Probes^a.

		human ρ1 GABAC receptor % inhibition and IC50 μM (95% confidence interval)
compound	spacer	300 μM	600 μMd	human α1β2γ2L GABAA receptor % inhibition at 300 μM
(S)-4-ACPBPA (6)		97 ± 3%b		inactiveg
		IC50 = 9.76, KB = 4.97 μMc
(R)-4-ACPBPA (7)		92 ± 7%b		inactiveg
		KB = 59.3 μMc
(S)-4-ACPBPA-C1-NMA [(S)-11a]	1		8 ± 2%
(S)-4-ACPBPA-C3-NMA [(S)-11b]	3		23 ± 4%
(S)-4-ACPBPA-C4-NMA [(S)-11c]	4		31 ± 2%
(S)-4-ACPBPA-C5-NMA [(S)-11d]	5		62 ± 7%	inactiveg
(R)-4-ACPBPA-C5-NMA [(R)-11d]	5		56 ± 9%	inactiveg
(S)-4-ACPBPA-C6-NMA [(S)-11e]	6		55 ± 3%
(S)-4-ACPBPA-C7-NMA [(S)-11f]	7		24 ± 8%
(S)-4-ACPBPA-C10-NMA [(S)-11g]	10		8 ± 3%
(S)-4-ACPBPA-C5-NBD (12)	5	IC50 = 281.42 (274.96–332.11)e		inactiveg
		IC50 = 193.27 (181.67–224.81)f
(S)-4-ACPBPA-C5-BODIPY (13)	5	IC50 = 103.14 (95.36–114.87)e		inactiveg
		IC50 = 58.61 (45.37–71.63)f
(S)-4-ACPBPA-C0-biotin (15)	0	inactiveb
(S)-4-ACPBPA-C5-biotin (16)	5	IC50 = 147.92 (139.45–174.13)e		9 ± 7%g
		IC50 = 76.54 (68.33–102.96)f

^aDetermined electrophysiologically in Xenopus laevis oocytes expressing the human ρ₁ GABA_C receptor or human α₁β₂γ_2L GABA_A receptors as previously described.^9,10

^bActivity or percent inhibition by 300 μM compound of the current produced by a submaximal concentration of GABA (1 μM, EC₅₀).

^cData from ref (9).

^dPercent inhibition by 600 μM compound of the current produced by a submaximal concentration of GABA (1 μM, EC₅₀), with a 5 min preincubation.

^eIC₅₀ values for compounds without preincubation.

^fIC₅₀ values for compounds with a 5 min preincubation.

^gActivity or percent inhibition by 300 μM compound of the current produced by a submaximal concentration of GABA (30 μM, EC₅₀) without and with a 5 min preincubation. All data are means ± the standard error of the mean (n = 3 oocytes).