Combined PDE-5 and ET
inhibition reverses pulmonary hemodynamic impairment and RV hypertrophy in SU-Hx rats. (A) Study design. Animals received 10 mg/kg each of tadalafil (TAD) and ambrisentan (AMB) once daily by oral gavage starting after week three. (B) Pulmonary artery acceleration time (PAAT) and velocity time integral (VTI) were quantified using Doppler images. Systolic notching of PA blood flow in an SU-Hx rat treated with vehicle is indicated. (C and D) PAAT and VTI were significantly reduced in SU-Hx rats compared to normoxic controls, indicating increased pulmonary arterial pressure. PAAT and VTI were rescued by TAD/AMB treatment. (E-G) M-mode echocardiographic images revealed increased RV anterior wall thickness in SU-Hx rats, which was dramatically reduced by TAD/AMB treatment. For all graphs, values represent mean +/-SEM. *P < 0.05 vs. SU-Hx + vehicle (Veh). Normoxia (n = 8); SU-Hx (n = 10); SU-Hx + AMB/TAD (n = 12).