Fig. 4

Class I and class III anti-arrhythmic drug responses of the control and long QT syndrome (LQT) type 1 and 2-specific cardiomyocyte clusters (hESC, WTa, WTb, LQT1A, LQT1B and LQT2). The drugs used were a sotalol, b quinidine and c E-4031. During E-4031 challenge all but one of the cardiac aggregates in hESC-CMs became arrhythmic or stopped beating at concentrations of 500–700 nM. Thus, error bars indicating standard deviation could not be calculated for these experimental points. Changes in the rate-corrected field potential duration (cFPD) were calculated as relative changes from the baseline for each cardiomyocyte cluster. Data is presented mean ± SD. Mean ΔcFPDs were normalized to baseline cFPD. Asterisks mark the statistical significance for mean ΔcFPD prolongation compared to baseline values. *p < 0.05, **p < 0.01, ***p < 0.001