Figure 3.

Comparison of the spontaneous currents, GABA-induced maxima and pentobarbital relative maxima to GABA for α₆β₂δ, α₆β₂γ, α₄β₂δ, α₁β₂γ, and α₁β₂δ receptors under equivalent expression conditions A, comparison of the spontaneous currents for α₆β₂δ, α₆β₂γ₂, α₄β₂δ, α₁β₂γ₂ and α₁β₂δ receptors under equivalent expression conditions. The α₆β₂δ receptor exhibited a significantly higher spontaneous current than did the other GABA_A receptors. B, comparison of the GABA-induced maximal current for α₆β₂δ, α₆β₂γ₂, α₄β₂δ, α₁β₂γ₂ and α₁β₂δ receptors under equivalent expression conditions. GABA maximal current was determined from experiments in A using GABA concentrations 20–50 times the respective EC₅₀ value. GABA had the lowest efficacy (maximal) for α₆β₂δ receptors. C, comparison of the relative maximal current of pentobarbital to GABA for the GABA_A receptor subtypes. Pentobarbital maximal current was determined from experiments in A using 1 mm concentration. Pentobarbital exhibited a significantly higher efficacy than did GABA for α₆β₂δ receptors.