Figure 3. The concentration-inhibition curve of thiopental for the kainate-induced current. The steady-state currents in the presence of thiopental were normalized to the average of the control currents before and after thiopental and plotted against the concentration of thiopental. A least-squares fit was performed using the Equation describedin materials and methods. The fitting procedure gave a concentration for 50% inhibition (IC (50)) of 49.3 +/- 5.6 [micro sign]M and Hill's coefficient of 1.17 +/- 0.14. Each point represents the mean of five to seven experiments, and the error bar indicates SEM when it is larger than the symbol.