Table 1.

Parameters obtained from fitting the Hill equation to GABA, β-alanine, taurine, I4AA, and 5α-THDOC data

GABAAR subtype	EC50 (μm)	nH	Imax (nA)	n
GABA-dependent activation
α6β2(1)δ				7
High-affinity component	0.005 ± 0.001	1.16 ± 0.11	259.50 ± 73.96
Low-affinity component	2.29 ± 0.85	0.56 ± 0.05	479.10 ± 123.94
Low expression	2.62 ± 0.39	0.63 ± 0.02	129.06 ± 10.72	9
Intermediate expression	0.46 ± 0.12	0.54 ± 0.02	317.39 ± 56.43	7
High expression	0.04 ± 0.009	0.65 ± 0.04	690.60 ± 80.23	11
α6β2(0.3)δ	1.52 ± 0.38	0.63 ± 0.03	362.80 ± 97.95	6
α6β2(0.1)δ	1.25 ± 0.21	0.74 ± 0.02	321.67 ± 50.62	10
α1β2(1)γ2S	2.87 ± 1.20	1.33 ± 0.10	2287.43 ± 237.76	7
α1β2(0.4)γ2S	10.61 ± 3.27	1.22 ± 0.10	2270.33 ± 354.79	6
α1β2(0.08)γ2S	37.20 ± 4.58	1.26 ± 0.14	974.33 ± 497.32	3
α1β2δ	6.45 ± 0.85	1.14 ± 0.05	510.02 ± 80.43	9
α6β2γ2S	22.30 ± 1.98	0.88 ± 0.14	484.00 ± 122.45	4
α4β2δ	1.53 ± 0.14	0.85 ± 0.03	338.09 ± 52.61	11
α6β2δR287M	3.71 ± 0.94	0.69 ± 0.18	44.67 ± 2.33	3
α6βY157Fδ				13
High-affinity component	0.37 ± 0.05	0.97 ± 0.04	355.54 ± 80.52
High-affinity component	104.65 ± 28.04	0.85 ± 0.14	389.23 ± 63.43
α6βY157F (0.1)δ	53.27 ± 13.99	0.94 ± 0.14	161.33 ± 36.99	3
I4AA-dependent activation
α6β2δ				4
High-affinity component	0.06 ± 0.01	0.82 ± 0.04	254.68 ± 52.02
High-affinity component	202.25 ± 17.71	2.61 ± 0.44	183.41 ± 16.77
β-Alanine-dependent activation
α6β2δ				5
High-affinity component	1.16 ± 0.72	0.89 ± 0.12	160.61 ± 69.75
High-affinity component	594.66 ± 142.86	0.67 ± 0.05	277.94 ± 64.02
Low expression	412.14 ± 68.76	0.71 ± 0.03	302.74 ± 58.79	10
Intermediate expression	111.86 ± 13.72	0.55 ± 0.15	426.33 ± 166.71	3
High expression	2.56 ± 1.52	0.59 ± 0.16	945.00 ± 76.51	3
Taurine-dependent activation
α6β2δ				3
High-affinity component	5.80 ± 0.84	1.03 ± 0.05	225.33 ± 43.42
High-affinity component	806.67 ± 193.50	0.91 ± 0.29	205.00 ± 40.31
Low expression	1817.58 ± 865.99	0.69 ± 0.06	145.40 ± 13.31	4
Intermediate expression	45.16 ± 25.57	0.55 ± 0.05	398.30 ± 63.92	3
High expression	6.03 ± 1.62	0.90 ± 0.10	607.63 ± 160.86	4
5α-THDOC-dependent activation
α6β2δ	0.89 ± 0.49	0.97 ± 0.06	550.67 ± 67.25	3