Figure 4.

Effect of WT-CAM (or GSH-CaM) (200 nmol/L) on Ca²⁺ SpF and SR Ca²⁺ content in (saponin-permeabilized) normal cardiomyocytes and failing cardiomyocytes treated with RyR2 domain peptides (DPc10, 30 µmol/L, or DP4090–4123, 30 µmol/L). SR Ca²⁺ content was measured by adding 10 mmol/L caffeine. Ca²⁺ spark images were obtained in the presence of the CaMKII inhibitor KN-93 (1 µmol/L). (A) Representative images of Ca²⁺ sparks. (B) Summarized data of the FDHM, FWHM, Ca²⁺ spark amplitude, Ca²⁺ SpF, and SR Ca²⁺ content. Data represent the means ± SD of 8–32 cells from each of three to four hearts.