Combined PDE-5 and ET
inhibition blocks RV hypertrophy and pro-hypertrophic calcineurin signaling. RV hypertrophy, as determined by comparing weights of RV vs. LV + septum (S) (A) or RV mass to tibia length ratio (B) was significantly reduced by combined TAD/AMB treatment. (C) LV hypertrophy was not observed in the model. *P < 0.05 vs. normoxia; †P < 0.05 vs. SU-Hx + vehicle (D) Immunoblotting revealed normalization of RCAN1 expression in RVs of animals treated with TAD/AMB, indicating suppression of calcineurin signaling. Calnexin served as a loading control. (E) Elevated RCAN1 expression was observed in LVs of some SU-Hx rats.