Fig. 7.

Cumulative activation ofI_KF. A, A sequence of 6 sec pulses to 0 mV were applied from a holding potential of −70 mV. The interpulse interval was varied from 2 sec (top traces) to 6 sec (middle traces) to 12 sec (bottom traces). The accumulation of g_KF was reduced by increasing the interpulse interval. The calibration bar refers to all three sets of traces. B, Increase in the amplitude of I_K at the end of the 6 sec pulse. The difference between the amplitude of the current at the end of the first pulse and at the end of each consecutive pulse is plotted. For the 2 sec interpulse period (black), the increase was large and did not saturate over the four pulses. For the 12 sec interpulse period (white), the increase was small and saturated. The 6 sec interpulse period (gray) was intermediate between the 2 sec interval and the 12 sec interval case in amplitude increase.