Figure 3. Lineweaver-Burk transformation of the effect of cholesterol on pentobarbital action. Data were recorded as described in methods. Suppression is measured as percent decrease in time-averaged current from control. Plotted are the data for channels in 4PE:1PC-membranes (0% cholesterol; circles = IC50of 845 plus/minus 72 micro Meter); 4%(weight/weight, corresponding to 7.3 mol%; squares = IC50of 1,451 plus/minus 97 micro Meter); and 10% cholesterol (weight/weight, corresponding to 17.3 mol%; triangles = IC50of 1,950 plus/minus 242 micro Meter). Linear regression fits have r2values of 0.96, 0.99, and 0.96, respectively. Data indicate a competitive inhibition of pentobarbital action by cholesterol at low cholesterol concentrations (below 10%).