Pharmacological inhibition of PARP (for 2 months) improves ESPVR and EDPVR in advanced aging-associated heart failure. Representative PV loops obtained with PV conductance catheter system at different preloads, showing difference in ESPVR and EDPVR between young adult (Y), aging (A), and aging treated with INO-1001 (A+INO-1001) rats. The less steep ESPVR in aging animals (middle panel) compared with control young adult rats (upper panel) indicates severely decreased contractile function in aging, which is improved by INO-1001 treatment (lower panel). The steeper EDPVR in aging rats indicates increased end-diastolic stiffness, which is also improved by INO-1001 treatment.