FIGURE 2

XE991 inhibits voltage-dependent outward currents in mPV cells. (a) Example of currents evoked by 200 ms depolarisation from -60 to +20 mV in the absence and when stably inhibited by 3, 10 and 100  M XE991. At each concentration of XE991 a pair of currents 60 s apart is shown to highlight the completeness of the block. (b) Representative time course of the inhibition produced by XE991. Each time point is the peak current amplitude at +20 mV. Recordings were made every 20 s. Gap in figure represents a period where a current voltage protocol was executed. (c) Concentration–response plots for XE991, C293B (present study) and linopirdine (taken from Ohya et al., 2003) against the gross outward current recorded at +20 mV. Each point is the mean of at least four cells with error bars representing the s.e.m. All plots were fitted with a logistic function. (d) Time course of K⁺ current inhibition by 10  M XE991 compared to that produced by 10  M C293B (). Arrow denotes start of block and the inhibition produced by both agents was fitted with a single exponential function. Time constants of current decay were 65 and 225 s for XE991 and C293B, respectively.