Figure 5.

Effect of Membrane Potential on Sodium-Channel Inhibition

(A) Schematic representation of patch clamp experiments carried out in isolated atrial cardiomyocytes. Human embryonic kidney (HEK) cells were patch clamped using the same setup. (B) Representative traces showing I_Na measured by patch clamping in isolated atrial cardiomyocytes, at baseline and with flecainide, at increasing holding potentials (–100 to –65 mV). (C) Reduction in peak I_Na was enhanced with increased holding potentials, irrespective of cardiomyocyte origin. (D) Representative traces showing I_Na in Na_v1.5-transfected HEK cells at baseline and with flecainide at increasing holding potentials (–100 to –65 mV). (E) Reduction in peak I_Na with flecainide in Na_v1.5-transfected HEK cells was enhanced with increased holding potentials. The greatest difference in percent reduction was between –70 and –65 mV. Abbreviations as in Figures 1, 2, and 3.