RYR2 expression level and phosphorylation level decreased while CaMKII activation level decreased in HF SAN. (a–c) Representative Western blots and quantification of RYR2-Total (a); RYR2-S2808 (b); and RYR2-S2814 (c) normalized to RYR2-total in SAN tissues from sham and HF mice. (d) Same as c, but in LVs from the same mice. (e) Representative Western blots and quantification of PP1C in SAN. (f and g) Representative Western blots and quantification of total and phosphorylated CaMKII (normalized by CaMKII-total) in SAN tissues (f) and ventricles (g) from sham and HF mice. The immunoblots in a, c, and f are the same as those of Fig. 3, a–c, respectively, exposed to different antibodies after stripping. Nonparametric Mann–Whitney U test was used.