Fig. 1. Reversible effects of azi-etomidate on α1β2γ2Lγ-aminobutyric acid type A (GABAA) receptors expressed in human embryonic kidney cells. Three sets of traces are shown from a single voltage-clamped HEK293 cell, illustrating the relative peak amplitudes and deactivation kinetics of currents elicited with 10 μm or 1 mm GABA in the absence or presence of azi-etomidate. Bars above the traces indicate the timing of GABA ( lower bars ) and azi-etomidate ( upper bar ) application. ( A ) Traces were recorded before azi-etomidate exposure: I10= 198 pA; I1000= 1020 pA; τw(weighted average time constant for deactivation) = 61 ms. ( B ) A single trace elicited with 10 μm GABA during exposure to 10 μm azi-etomidate: I10= 785 pA; τw= 950 ms. ( C ) Traces were recorded after azi-etomidate exposure and a 2-min wash: I10= 206 pA; I1000= 1030 pA; τw= 78 ms. ( D ) Average normalized (to 1 mm GABA control) GABA-induced peak currents from HEK293 cells and patches in the absence ( circles , four cells) and presence ( squares , four cells) of 3.2 μm azi-etomidate. Fitted GABA EC50values in the absence and presence of azi-etomidate are, respectively, 43 ± 5.3 μm and 7.0 ± 0.54 μm. ( E ) 200 μm azi-etomidate was used to stimulate current from an excised outside-out membrane patch. Azi-etomidate application is indicated by the bar above the trace. The current desensitizes during azi-etomidate application with a time constant of 22 ± 0.4 s. The steady-state current after desensitization is 12% of peak.