Difference in the Ca²⁺ spark characteristics between intact versus permeabilized myocytes after myocardial infarction. (A–C) Ca²⁺ spark amplitude (A; peak F/F₀), duration at half-peak amplitude (B; FDHM), and width at half-peak amplitude (C; FWHM) in intact myocytes from sham (n = 442 Ca²⁺ sparks, from 22 cells, from three hearts) and PMI mice (n = 160 Ca²⁺ sparks, from 24 cells, from three hearts). (D–F) Same as A–C but in permeabilized myocytes from sham (n = 7,806 Ca²⁺ sparks, from 26 cells, from three hearts) and PMI (n = 9,783 Ca²⁺ sparks, from 27 cells, from three hearts) mice. **, P < 0.01; ***, P < 0.001 versus myocytes from sham mice. Error bars represent the SEM.