Figure 3.

Concentration–response plots previously obtained for 2,6-dimethylphenol, 3,5-dimethyl-4-chlorophenol, and 4-chlorophenol. Each symbol represents the mean value derived from at least three different experiments; error bars are standard deviations. The solid lines show the fits of equation (11) (left) or its modification (right) with the indicated parameters. The slope factor k of 7.4 and the respective values of K_dR or ECR₅₀, respectively, were entered into the model as constant factors. The Hill coefficients for binding to resting channels were equal to or very close to one for all compounds. The modification improved the fit for (from top to bottom) 2,6-dimethylphenol, 3,5-dimethyl-4-chlorophenol, and 4-chlorophenol, yielding values for the Hill-type exponent n for binding to fast-inactivated channels that were significantly greater than one in each case.