Figure 2. Single channels have three identical conductance levels for synaptic- and extrasynaptic-type GABA_A receptors A–C, single channel currents induced by GABA.

(A), muscimol (B) and THIP (C) on recombinant α1β3γ2 (a), α4β3γ2 (b) and α4β3δ (c) receptors. D, typical current amplitude histogram (α1β3γ2, 3 μm GABA) showing curve fits with three Gaussians each (dotted lines) and their sum (continuous line). E, three conductance levels (high, 26–31 pS (squares); intermediate, 17–22 pS (circles); low, 11–14 pS (triangles)) were resolved for all three agonists at three concentrations (low EC_5-20 (white); intermediate EC_40-60 (grey); and high EC_80-100 (black)) (n= 5–7; mean ±s.e.m.). See Table 1 for agonist concentrations. F, relative areas of the single channel conductances for all three agonists at each receptor isoform, at three concentrations.