Figure 5. Effect of different concentrations of PHT on I_NaP evoked using inactivating prepulses of different durations.

Panels A and B show the dose response curves with prepulses of 200 ms (A) or 500 ms (B); higher concentrations of PHT have not been used because of its solubility limits, and the maximal block was not reached. The solid lines are fit to rectangular hyperbolas that gave apparent IC₅₀ values of 28 and 18 µM and apparent maximal block of 24 and 26% respectively. All of the PHT concentrations used induced a statistically significant reduction of I_NaP peak amplitude with both 200 and 500 ms inactivating prepulses, as shown in C (**p<0.01; *** = p<0.001; ANOVA test).