Fig. (5) Assessment of pharmacological agents on cardiac function in a normal mouse. Baseline images (first column) acquired prior to an infusion of dobutamine (middle column). In addition, the effect of the beta blocker esmolol (right column) is subsequently shown to counteract the increased contractility caused by the cardiac stress agent dobutamine. ED; end diastolic, ES; end systolic time frames. The scale bar represents 5 mm.