Echocardiographic and hemodynamic changes with dubutamine stimulation after small MI. A: Echocardiographic findings at 7 weeks after MI with dobutamine stimulation (baseline, 5, and 10 μg/kg/min for MI [n = 5] and sham groups [n = 5]) under xylazine/ketamine anesthesia. Significant heart rate increases were noted in MI group at 10 μg/kg/min, but not in sham group. %FS did not significantly change in response to dobutamine in either group, although there is a mild dose-dependent positive trend in sham mice. #p < 0.05 vs. baseline. B: Hemodynamic data by cardiac catheterization at 7 weeks in MI (n = 5) and sham group (n = 5) with dobutamine stimulation (baseline, 5 μg/kg/min, and 10 μg/kg/min). LVSP was comparable between MI and sham at the baseline but became significantly higher in sham than in MI with maximum dobutamine stimulation. LVEDP was significantly higher in MI than in sham group at the baseline, and these values did not significantly change with dobutamine stimulation. Maximum response in (+)dP/dTmax and (−)dP/dTmax by dobutamine infusion from baseline were shown. Even at the baseline, sham hearts showed better systolic and diastolic LV function than MI hearts. In addition, sham hearts had better response to dobutamine stimulation for both systolic and diastolic function. * p < 0.05 vs. sham; # p < 0.05 vs. baseline.