Direct activation of α₁β₃γ_2L γ-aminobutyric acid type A (GABA_A) receptor currents by etomidate and naphthalene–etomidate. (A) Electrophysiologic traces showing the direct activation by etomidate (top) or naphthalene–etomidate (bottom). To allow a direct comparison between drugs, a single oocyte was used to obtain both data sets. (B) Etomidate and naphthalene–etomidate concentration-response curves for direct activation. Each symbol is the mean ± SD derived from four different oocytes. The curve is a fit of the etomidate data set to equation 1 yielding a half-maximal direct activating concentration, maximum current amplitude at high etomidate concentrations, and slope of 65 μM (95% CI, 41 to 103 μM) and 54% (95% CI, 46 to 63%), and 1.2 (95% CI, 0.7 to 1.8), respectively. A fit of the naphthalene–etomidate data set to equation 1 did not converge.