Fig. 5.

Calcium relaxation for mdx and WT. A: representative calcium transients at the base of a WT (blue line) and a mdx (red line) heart. Signals were averaged from adjacent 25 charge-coupled device elements. Definitions of T₅₀ and decay constant τ are illustrated. B and C: representative T₅₀ and decay constant maps in a mdx and a WT heart under unloaded vs. stretched condition. D and E: under unloaded conditions, both T₅₀ and decay constant were comparable between mdx and WT hearts. Ventricular stretch caused regional increases of T₅₀ and decay constant at the base of mdx hearts. However, WT hearts exhibit similar T₅₀ and decay constant. *P < 0.05; **P < 0.01.