Figure 3. Concentration-response curves for R(+) etomidate potentiating the current induced by 1 micro Meter gamma-aminobutyric acid (GABA). Each data point represents the mean peak current from an average of 20 cells, and the error bars are SEMs. Where the error bar is not shown it was smaller than the size of the symbol. The line is an unweighted least-squares fit of the data to a Hill equation (see Materials and Methods, Equation 3) with a half-maximal effective concentration of 40 +/- 9 micro Meter, a maximal potentiation of 3,200 +/- 300%, and n^H= 1.06 +/- 0.13. The inset on the left shows typical current traces for 1 micro Meter GABA, with and without 3 micro Meter R(+) etomidate, whereas the inset on the right shows typical current traces for 1 micro Meter GABA, with and without 300 micro Meter R(+) etomidate. In both insets the control current trace is labeled “C”.