Dobutamine stress echocardiography. M-mode short-axis views of the left mid-ventricle before and after β-adrenergic stimulation with dobutamine in an 18-month-old A) C57Bl/6J, B) IGF-II/LDLR-/-ApoB100/100 and C) LDLR-/-ApoB100/100 mouse. Compared to the C57Bl/6J control, IGF-II/LDLR-/-ApoB100/100 and LDLR-/-ApoB100/100 mice show reduced contractility. D) Regional wall motion analysis represents improvement of systolic function after dobutamine in all mouse strains, although statistically significant only in LDLR-/-ApoB100/100 mice. Results are mean ± SD of 5 (LDLR-/-ApoB100/100 and IGF-II/LDLR-/-ApoB100/100) or 6 animals (C57Bl/6J).