Fig. 3. Morphology and Ca²⁺ transients in intact cardiomyocytes.

a Representative images of cardiomyocytes. b Summarized data of cell width, cell length, and cell area in isolated cardiomyocytes. N = 250–400 cells from 3–5 hearts. c Representative recordings of sarcomere shortening and fluo-4AM fluorescence signal, at a pacing rate of 1 Hz. d Summarized data of sarcomere shortening, peak Ca²⁺ transient, time from peak to 70% decline of Ca²⁺ transient, and sarcomere shortening. N = 22–31 cells from 3 to 6 hearts. Values for individual mice are plotted together with mean ± SEM. Parentheses indicate the number of mice. *P < 0.05, **P < 0.01, ***P < 0.001 (one-way ANOVA with post-hoc Tukey’s multiple comparison test).