Effects of prilocaine and pramoxine on CAPs recorded from frog sciatic nerve fibers. (A, C) CAP peak amplitudes are reduced by prilocaine (1 mM; A) and pramoxine (0.5 mM; C); the reductions were reversible and partially reversible, respectively. Top of figure: recordings of CAPs in the control, at 20 min after exposure to prilocaine (A) or pramoxine (C), and after washout of prilocaine (30 min; A) or pramoxine (60 min; C). Bottom of figure: average time course of changes in CAP peak amplitudes following exposure to prilocaine (A) or pramoxine (C) for 20 min, relative to that before exposure, obtained from 5 or 4 sciatic nerves. (B, D) Plot of the peak amplitudes of CAPs, relative to control, recorded from sciatic nerve fibers treated with prilocaine (B) or pramoxine (D) at various concentrations for 20 min. Each of the data points was obtained from 3 to 5 sciatic nerves. The concentration-response curve was drawn according to the Hill equation (B: IC50=1.8 mM, nH=1.7; D: IC50=0.21 mM, nH=1.2).