Extended Data Fig. 8: Spark characteristics in wild-type cells.

In cardiomyocytes isolated from wild-type mice, ISO treatment increased spark rate within the cell interior (a), but not the proportion of multirelease events (b) or the displacement of the spark centroid during its time course (radius of gyration, c). These findings closely paralleled observations made in knock-in cardiomyocytes (Fig. 7). Data are presented as mean ± SEM. Differences between groups were tested with two-tailed linear mixed models with Tukey post hoc correction for multiple comparisons. *** = P < 0.001. P values: a: 0.0538; b: 0.287; c: Ctl vs Iso 0.8425, Ctl single vs Ctl multi <0.0001, Iso single vs Iso true: <0.0001. For spark rate and multirelease proportion measurements, n = control: 3 animals, 35 cells; iso: 3 animals, 34 cells. For radius of gyration measurements, n = control_{single release}: 3 animals, 13 cells, 45 sparks; control_{multi release}: 3 animals, 9 cells, 15 sparks; iso_{single release}: 3 animals, 21 cells, 82 sparks; iso_{multi release}: 3 animals, 17 cells, 47 sparks.