FIGURE 1.

Effect of 200 μmol/liter FLEC on Kv2.1 K⁺ currents and conductance. A, open probability curves of mean conductance values from eight experiments. Inset, original recording of one experiment (maximal amplitude, 21.7 μA; voltage step duration, 500 ms). Shown are potential steps from −80 to +60 mV under control conditions (CTRL, open circles) and with FLEC (filled circles). The conductance values (G_rel) were normalized to the respective maximal value under control conditions. B, change of fractional current (I_rel), i.e. fraction of current with FLEC relative to current under control conditions (CTRL), with the duration (t) of voltage steps to +60 mV (except for the first 8 ms). The trace is the mean of seven experiments. Hatched line, fit of I_rel with a monoexponential function. The fit is shown from 0 to 250 ms of the voltage step. Inset, original recording of currents at +60 mV (maximal amplitude, 25.7 μA; voltage step duration, 200 ms). C, voltage dependence of a fraction of block. The half-blocking concentrations (K_D) at different potentials are given as mean ± S.E. of six experiments (filled circles, dotted line). The hatched line gives the open probability curve obtained by fitting the relative conductance values (G_rel) current amplitude with a Boltzmann equation. The fit was performed with the measured K_D⁰ of 263 μmol/l (δ₁ = 0.17 ± 0.01) and with an unknown K_D⁰ (δ₂ = 0.10 ± 0.03, K_D⁰ = 200 μmol/liter; n = 6, solid lines). The error bars indicate S.E. MP, membrane potential.