Examples (Fig 4A) and group means (Fig 4B) of effects of Rp-cAMP and PTX on Ang-(1-12) induced changes to LV myocyte contractile functional performance in normal and HF. The Ang-(1-12)-induced inotropic effects were completely prevented in the presence of an inhibitory cAMP analog, Rp-cAMPS (10−4 M 2 h) in both normal and HF myocytes, but were further augmented only in HF after the incubation of myocytes with the Gi inhibitor, pertussis toxin (PTX, 2 μg/mL, 36°C, 5h). * p<0.05, Ang-(1-12) vs corresponding baselines. ** p<0.05, Ang-(1-12)-caused changes in pretreated myocytes vs Control Ang-(1-12)-resulted changes.