PDE5A and pulmonary arterial hypertension: In contrast, PDE5 expression levels in MCT-treated lung tissues showed no differences when compared to Control group, however, a significant increase was observed in WGLL in comparison to PAH group animals (Control: 1.367 ± 0.189; WGLL: 2.329 ± 0.094; Sildenafil: 1.968 ± 0.209 vs. PAH: 1.029 ± 0.079; in arbitrary units).