Figure 3. Voltage and K⁺ dependence of the sulphonylurea-sensitive run-up current.

A, shows the whole-cell membrane current in response to ramping the membrane potential (V_m) from –126 to –47 mV (ramp 80 mV s⁻¹) following current run-up and after subsequent application of glibenclamide (30 nm). B, I–V relationship of the glibenclamide-sensitive component of the current shown in A. C, examples of the extremes of rectification observed in the I–V relation of the sulphonylurea-sensitive from different cells. D, the reversal potentials of the sulphonylurea-sensitive current measured in 3, 6 and 10 mm[K⁺]_o were 91.4 ± 0.94, –74.5 ± 1.01 and –59.9 ± 1.17 mV (n = 5), respectively, slope 59.6 mV for a 10-fold change in [K⁺]_o.