Fig. 1.

A: concentration dependence on the genistein-induced inhibition of voltage-dependent K⁺ channel (Kv) 4.3. Whole cell Kv4.3 currents were elicited by 500-ms step depolarization to +40 mV from a holding potential of −80 mV at 10-s intervals. The control current and currents following the addition of 10, 30, 100, and 300 μM genistein are indicated. The reduction in the peak amplitude of Kv4.3 current at +40 mV was used as an index of inhibition. B: reversible inhibition of Kv4.3 by genistein. Whole cell currents were elicited by 500-ms depolarizing pulses of +40 mV from a holding potential of −80 mV at 10-s intervals under control conditions and in the presence of genistein. The time course of inhibition in the presence of 100 μM genistein is shown. Maximal inhibition occurred ∼1 min after drug application began. Complete recovery from inhibition was observed after washout of the drug. The steady-state amplitudes of the currents were plotted as a function of time. The bar indicates the time of genistein application. Values are means ± SE.