Effects of tetrodotoxin on I_Na,late in ventricular and atrial cardiomyocytes (CM) from ΔKPQ-SCN5A mice.

<p><b>A</b> and <b>B</b>: Voltage clamp protocol Ⅰ and examples of original current tracings recorded in ΔKPQ mouse myocytes under control conditions or in the presence of 10 μM tetrodotoxin (TTX). Late sodium currents were measured at the end of the 250 ms-long pulse at -30 mV (black arrow). As internal control, current amplitude was also measured at -80 mV and -110 mV (white arrows). <b>C</b>: Current densities were plotted for each voltage without (control, black circles) and after addition of 10 μM TTX (open squares). <b>D</b>: Currents measured at -30 mV before (black columns) and after TTX exposure (grey columns) in myocytes from wild type (WT) and ΔKPQ mice. Numbers below the columns (x/y) indicate number of cells per number of animals. TTX-sensitive current expressed as current density (in pA/pF). **P < 0.01; ***P < 0.001; paired Student’s t-test.