Figure 3.

Disopyramide reduced arrhythmic events in SQTS1-hiPSC-CMs. Calcium transients were measured in spontaneously beating cells. Then carbachol (10 µM) plus epinephrine (10 µM) was applied to cells to trigger arrhythmic events. In cells showing arrhythmias, disopyramide (10 µM) was applied to the cell in presence of carbachol and epinephrine. (A) Representative traces of calcium transients in a cell before challenging (Ctr). (B) Representative traces of calcium transients in the cell challenged by carbachol plus epinephrine (CCh+Epi). (C) Representative traces of calcium transients in the cell in the presence of carbachol plus epinephrine and disopyramide (CCh+Epi+Dis). (D) Averaged values of arrhythmic events per minute. CCh+Epi slowed the beating but led to small and irregularly triggered beating. The arrhythmic events were defined as transients that are larger than 10% but smaller than 80% of the normal regular transients. The arrows indicate arrhythmic events. (E) Mean values of the amplitude of calcium transients in absence (Ctr) and presence of disopyramide (10 µM). (F) Mean values of the duration of calcium transients. (G) Mean values of the diastolic baseline of calcium transient. Shown are mean ± SEM, n represents number of cells. p values were determined by One Way ANOVA followed by Holm-Sidak method (D) or paired t-test (E–G). ns, not significant.