Figure 4. Acceleration of the average outward current decay by internal spermine.

Outward currents through WT channels were elicited by depolarizing steps from −48 mV to +40 mV every 1 s. Capacitive and leakage currents were removed by subtracting from each trace the average of current traces with 20 mm TEA-Cl. The average current was obtained from 72–106 frames. The time constant of the exponential decay (shown by the continuous line) was 172 ms in the control, 71.9 ms with 1 nm spermine, 17.9 ms with 10 nm and 2.39 ms with 100 nm. The straight line before and after the step pulse corresponds to the zero-current level. The residual steady-state current during the pulse with 10 nm spermine is due to incomplete subtraction of leakage currents.