Fig. 4.

Evidence of reduced left and right ventricular systolic function in old mdx mice. A dobutamine stress test was performed to assess cardiac reserve of both right and left ventricles of C57BL/10 and mdx hearts. These tests reveal significantly reduced cardiac reserve of both right and left ventricular systolic pressures (A and B) and maximum dP/dt (C and D) in mdx hearts compared with C57BL/10. E: dobutamine significantly increased the preload recruitable stroke work, a load-independent measure of contractility, in both mdx and C57BL/10 hearts. ‡P < 0.05, significant difference between genotypes. *P < 0.05, difference from baseline C57BL/10. †P < 0.05, difference from baseline mdx.