Figure 6:
Adrenergic-dependent phase 3 EADs and spontaneous Ca2+ oscillations in R67Q+/− mice. A. Representative traces from action potential recordings (left) and calcium transient measurements (right) showing phase 3 EADs and spontaneous Ca2+ release events, respectively, from isolated R67Q+/− ventricular myocytes. B. R67Q+/− myocytes had more EADs at baseline (23 ± 14.2 events) and following ISO (42.8 ± 19.6 events) compared to WT (0 events at baseline, 1.5 ± 1.5 events following ISO) (left panel) during action potential measurements and increased spontaneous release events following ISO during calcium transient measurements (right panel). C. Analysis of take off potential revealed depolarized potential compared to classical phase 2 EADs, with delayed onset from stimulus. D. Linear regression of take off potential vs peak voltage reached by phase 3 EADs in R67Q+/− myocytes. (Animals/cells for EAD analysis: WT – N=3, n=7; R67Q+/− - N=2, n=5. Animals/cells for spontaneous event analysis - WT – N=6, n=7; R67Q+/− - N=4, n=10). Two-way repeated measures ANOVA with post-hoc Bonferroni correction was used (6B), or non-linear regression (6C, 6D).