Figure 8. Qd removal as a function of [K⁺]_o.

A, left panel, control I_K at +40 mV recorded in 40K_o/K_i solutions. After checking the stability of control I_K, the cell was superfused for 45 s with 40K_o+ 0.1Qd and 22 +40 mV/30 ms pulses were applied to repeatedly block the channels (as in Fig. 7, not shown, indicated by the arrow). Immediately after the last I_K with Qd was recorded (labelled 0, right panel) the cell was superfused with the 40K_o solution while +40 mV pulses were applied at 1.7 Hz, to follow Qd removal (vertical arrow). B, superimposed I_K before (Control) and after Qd removal. There was a complete recovery. C, time course of Qd removal. I(t) is the average amplitude of I_K measured at the end of each pulse at time t of the cell perfusion with 40K_o, as in A right panel, and I_max is the maximal, steady-state I_K (n= 3). The line is the fit of the points with the equation: I(t)/I_max= 1 − exp(t/τ), with τ= 9.6 s. D, 1/τ as a function of [K⁺]_o. 1/τ was obtained from the fit of complete recovery curves as in C (n= 3 at each [K⁺]). The dotted line signals the average rate of Qd removal.