Figure 2. Electrical stimulation regulates automaticity in human stem cell-derived cardiomyocytes.

(a) Fractional area change as a function of time after 7 days of stimulation. Dark and light traces represent two independently beating areas within the same field of view. (b) Frequency of autonomously beating cardiomyocytes as a function of duration of stimulation (average±s.e.m., n=30, P<0.05). (c,d) Strain rate per beat and the cumulative contraction strain (average±s.e.m., n=3, P<0.05). (e) Calcium fluorescence traces for an entire beating area over time. (f) Normalized fluorescence intensity over one beat. (g) Full width half maximum (FWHM) calcium transients for stimulated groups (average±s.e.m., n=23, P<0.05). *Statistically significant differences between groups, testing was done using one-way ANOVA with post hoc Tukey tests.