Fig. 1.

Direct activation of GABA_A receptors by THDOC. A, Representative currents evoked by increasing THDOC concentrations for α1β3γ2L (▪), α1β3δ (▾), α6β3γ2L (■), α6β3δ (▿), α1β3 (●), and α6β3 (○) GABA_A receptor isoforms. The hatched bars indicate application of various THDOC concentrations. Note the small inflections in the currents after application of 30 μm THDOC. B, Concentration jump using 10 μm alphaxalone shows a rebound current more clearly because of faster solution exchange (see Materials and Methods).C, Concentration–response relations for direct activation by THDOC. Mean ± SEM current amplitudes are shown. Theleft and right panels show α1- and α6-containing isoforms, respectively. Smaller currents were observed for δ subunit-containing isoforms. Symbols are as inA. See Table 1 for fitted parameters.