Fig. 2.

Response of LV function during 20 min of acute physiological demand. (A–C) LVDevP, HR, and RPP, the product of LVDevP and HR, measured in isolated hearts perfused at baseline (BL) and dobutamine infusion (n = 5 each group). (D) Coronary flow, estimated by collecting the perfusate effluent over a 2-min period, in Langendorff heart preparations during normal workload and dobutamine infusion (n = 5 each group). (E and F) Rate of pressure change calculated by the first derivative of the LV pressure wave (dP/dt) in Langendorff heart preparations at baseline and during dobutamine infusion. The positive maximum (+dP/dt) is an index of the rate of LV pressure development. The negative maximum (−dP/dt) is an index of the rate of ventricular relaxation. *P < 0.05 vs. WT at baseline (n = 5 each group).