Fig. 2

CPZ facilitates the inactivation of Kv1.3 Channel. A–D The activation and inactivation traces were fitted by single exponential functions, and the time constants of activation and inactivation processes were estimated from traces elicited by a single 2-s + 50 mV pulse from a holding potential of − 60 mV. A Representative normalized current traces of the activation phase in the absence and presence of 30 and 100 µM CPZ for 12 min. Each current trace was normalized to its peak value. B Time-constant values of activation processes with and without 30 and 100 µM CPZ (n = 5–7). C Representative normalized current traces of the inactivation phase in the absence and presence of 30 and 100 µM CPZ for 12 min. Each current trace was normalized to its peak value. D Time-constant values of inactivation processes with and without 30 and 100 µM CPZ (n = 9–10). E Typical steady-state activation tail currents measured at − 50 mV following 100-ms depolarizing pulses from − 70 to + 50 mV with and without 100 and 300 µM CPZ. F Steady-state activation curves obtained by normalizing each tail current to the tail current at + 50 mV and fitting the data to a Boltzmann equation (n = 6–7). G Typical tail currents evoked by 200-ms depolarizing pulses to + 40 mV; 30-s preconditioning pulses from − 70 to 0 mV with and without 100 and 300 µM CPZ. H Steady-state inactivation curves obtained by normalizing each tail current to the tail current when depolarized to + 40 mV and fitting the data to a Boltzmann equation (n = 7–8). *P < 0.05. I A double-pulse protocol was employed to investigate the recovery of Kv1.3 from inactivation, both in the absence and presence of CPZ. The first pulse consisted of a 200 ms depolarizing pulse to + 40 mV from a holding potential of − 80 mV, followed by a second identical pulse after varying interpulse intervals ranging from 10 ms to 30 s at − 80 mV. Pulses were delivered at intervals of 30 s. J The solid lines represent the single exponential fits of the peak amplitudes of Kv1.3 currents as a function of the interpulse interval (n = 4–5). Values are shown as mean ± S.E.M