Figure 5.

Dobutamine cardiac stress testing of dystrophic hearts. Intravenous infusion of dobutamine (42 μg/kg/min) was used to assess cardiac reserve in several models of dystrophic cardiomyopathy. A) Dobutamine infusion begins at time 0 and proceeds for 30 min or until a minimal pressure cutoff was reached. Kaplan-Meier survival curve analysis provided the P values compared to control mice. B) PRSW provides evidence of limited cardiac reserve in dystrophic hearts. C) Ejection fraction is a clinically relevant measure of global cardiac pump function, which was significantly increased by dobutamine in wild-type and γ- and δ-SG-null mice, but not in mdx mice. Results were derived from 7–9 animals. *P < 0.05 vs. baseline cardiac function; t test.