Figure 1
Responses to GABA site ligands. GABA and gaboxadol sensitivities of recombinant α3β1, α3β1γ2, α3β1θ, α3β1ε and α3β1θε GABAA receptors expressed in Xenopus oocytes. A. The values for currents induced by various GABA concentrations are given as means ± standard errors (n = 8 for α3β1, n = 6 for α3β1γ2, n = 7 for α3β1θ; n = 6 for α3β1ε and n = 7 for α3β1θε receptors). GABA dose-response curves were obtained by non-linear regression fits and GABA EC50 values were calculated for individual cells, being 55 ± 6 μM for α3β1 receptors, 200 ± 38 μM for α3β1γ2 (p < 0.01, unpaired t-test from α3β1), 2.3 ± 0.5 μM for α3β1ε (p < 0.001 from α3β1) and 81 ± 18 μM for α3β1θ (p > 0.05) and 35 ± 9 μM for α3β1θε receptors. Maximal currents elicited by GABA were 1.5 ± 0.9 μA for α3β1, 2.2 ± 0.5 μA for α3β1γ2, 1.2 ± 0.3 μA for α3β1θ; 1.2 ± 1.0 μA for α3β1ε and 0.9 ± 0.4 μA for α3β1θε combinations. B. Gaboxadol-induced currents are given as means ± standard errors (n = 7 for α3β1, n = 5 for α3β1γ2, n = 4 for α3β1θ; n = 5 for α3β1ε and n = 4 for α3β1θε receptors). Gaboxadol dose-response curves were obtained by non-linear regression fits and the EC50 values were calculated for individual cells, being 139 ± 19 μM for α3β1 receptors, 411 ± 13 μM for α3β1γ2 (p < 0.05, unpaired t-test from α3β1),72 ± 5 μM for α3β1ε (p > 0.05 from α3β1), 224 ± 20 μM for α3β1θ (p > 0.05) and 165 ± 19 μM for α3β1θε receptors. Maximal currents elicited by gaboxadol were 2.5 ± 0.9 μA for α3β1, 1.2 ± 0.5 μA for α3β1γ2, 0.55 ± 0.2 μA for α3β1θ, 1.0 ± 0.4 μA for α3β1ε and 0.8 ± 0.3 μA for α3β1θε combinations.