Phosphorylation of RyR2 Ser‐2814 by CaMKII mediates β1‐adrenergic stress induced Ca²⁺‐leak from the sarcoplasmic reticulum

Fig. 1. Ca2+‐transient amplitude and decay kinetics. Mean data for Ca2+‐transient amplitudes (A) and decay kinetics (rt50%) (B) show that both the increase of Ca2+ amplitude and the acceleration of Ca2+ transient decay are strong in both genotypes upon ISO stress and not different between genotypes. Data are shown as means ± SEM (n = cells/mice; one‐way ANOVA).

Fig. 2. Tetracaine‐sensitive SR Ca2+ leak. Original recordings (A) show tetracaine‐sensitive SR Ca2+ leak in S2814A and WT mice under ISO stimulation. Mean data (B) show protection from ISO‐induced SR Ca2+ leak in phosphoresistant RyR2 S2814A mice as compared to WT mice (P = WT‐NT vs. WT‐ISO; P = WT‐ISO vs. S2814A‐ISO). Also, ISO‐induced worsening of leak/load relationship (C) was completely prevented in S2814A compared to WT cells. Data are shown as means ± SEM (n = cells/mice; one‐way ANOVA).

Fig. 3. Postrest potentiation of systolic Ca2+ release. Original recordings (A) show postrest potentiation of S2814A and WT cells under β‐adrenergic stimulation with ISO. Original recordings from S2814A are depicted time‐shifted vs WT to be visually better discernible. Mean data (B) show that postrest potentiation of systolic Ca2+ release was significantly better preserved in S2814A mice under ISO stress compared to WT mice. Data are shown as means ± SEM (n = cells/mice; one‐way ANOVA).

Fig. 4. Phosphorylation level of Ser‐2814 and Ser‐2808. Examples of protein expression (A) in WT and S2814A mice with or without ISO stimulation. Mean data of Ser‐2814 (B) and Ser‐2808 (C) phosphorylation levels show phosphoresistance at Ser‐2814 in S2814A mice, while phosphorylation levels at Ser‐2808 were significantly increased upon ISO stress both in WT and S2814A mice. Data are shown as means ± SEM (n = mice; one‐way ANOVA).