(B) In vivo hemodynamic response to the β1,α1-adrenergic agonist dobutamine. Male and female PGC-1α+/+ (n = 6) and PGC-1α−/− (n = 6) mice at 10–12 wk of age were anesthetized and a 1.4-French Millar catheter was placed through the carotid artery into the left ventricle as described in Materials and Methods. Heart rate (left graph) and a measurement of ventricular systolic performance, dP/dt (right graph), were measured following infusion of dobutamine. * p < 0.05.