Fig. 6: β-adrenergic stimulation increases RyR recruitment during Ca2+ sparks.
a,b, ISO treatment did not alter the proportion of total sparks which exhibit multiple releases (a) or their travel distance (b). c–f, However, the amplitude of each DS Ca2+ release event was larger during ISO (c), resulting in larger overall Ca2+ sparks (d), without increasing spark time to peak (e) or duration (f). Data are presented as mean ± s.e.m. Differences between groups were tested with two-tailed linear mixed models with Tukey post hoc correction for multiple comparisons. *P < 0.05, **P < 0.01, ***P < 0.001. Please refer to Source data for exact P values and n values. g, Experimentally measured spark amplitudes and corresponding weighted RyR counts were plotted, together with the theoretical maximal spark amplitude curve (see also Fig. 4d). h, ISO produced an upward shift, as sparks skewing toward larger amplitudes. i, Using the mathematical model to calibrate the number of open RyRs during each spark revealed a similar skewing towards larger values during ISO treatment.
