Fig. 4.
Flecainide decreases polyamine blockade. (A) IKir2.1 normalized to the amplitudes at −120 mV at potentials positive to EK in control conditions and in the presence of flecainide. (B) Mean relative Gc in control conditions and in the presence of flecainide. Solid lines represent the fit of a Boltzmann function to the data. (Inset) Mean I–V curve and the current predicted, assuming a linear unblocked current in control conditions. (C) Current traces recorded at +70 mV in excised inside-out patches from HEK-293 cells expressing Kir2.1 channels in control conditions and after cytoplasmic surface application of Spm in the absence and presence of flecainide. Dashed lines represent the zero current level. (D) Percentage of current inhibition at +70 mV in excised inside-out patches as a function of Spm concentrations in the absence and presence of flecainide. (E) I–V curves for E224A Kir2.1 channels in the absence and presence of flecainide. (F) Flecainide-induced change on the current recorded at −50 mV in CHO cells expressing WT, E224A, E299A, and D259A Kir2.1 channels. *P < 0.05 vs. control. Each point/bar represents the mean ± SEM of five or more experiments.