Fig. 5.

Sub-nanomolar concentrations of muscimol evoked currents on recombinant δ subunit-containing GABA_ARs. Representative concentration-response data (out of 3 similar recordings made using injections into different batches of oocytes) using muscimol concentrations from 0.1 nM up to 100 mM on (A) α4β3δ- or (C) α4β3-injected oocytes. Muscimol concentrations from 0.1 nM to 30 nM activate currents only in α4β3δ-injected oocytes, but not in the absence of δ subunits in α4β3 injected oocytes. (B) Slow current activation (association rates are slow at these low muscimol concentrations because association is concentration-dependent) and also current deactivation at the lowest doses (expanded in B) and the two-component decay for doses ≥10 nM. (D) Superimposed responses to 300 nM muscimol from α4β3δ- and α4β3-injected oocytes. The responses were scaled so that the α4β3 300 nM muscimol current fits the fast current component in α4β3δ-injected oocytes.