One of the most common and potentially life-threatening electrolyte disturbances is hypokalemia, characterized by low concentrations of K<sup>+</sup> Using a multielectrode array platform and current clamp technique, we investigated the effect of low extracellular K<sup>+</sup> concentration ([K<sup>+</sup>]<sub>Ex</sub>) on the electrophysiological properties of hiPSC-derived cardiomyocytes (CMs) generated from a healthy control subject (WT) and from two symptomatic patients with type 1 of LQTS carrying G589D (LQT1A) or IVS7-2A>G mutation (LQT1B) in <i>KCNQ1</i> The baseline prolongations of field potential durations (FPDs) and action potential durations (APDs) were longer in LQT1-CMs than in WT-CMs.
Sinus node function and ventricular repolarization during exercise stress test in long QT syndrome patients with KvLQT1 and HERG potassium channel defects.