Buffered l-ascorbic acid, alone or bound to KMUP-1 or sildenafil, reduces vascular endothelium growth factor and restores endothelium nitric oxide synthase in hypoxic pulmonary artery

Ascorbic acid bound to KMUP-1 and sildenafil were examined for their antioxidant effects on vascular endothelium growth factor (VEGF) and endothelium nitric oxide synthase (eNOS) in hypoxic pulmonary artery (PA). Inhaled KMUP-1 and oral sildenafil released NO from eNOS. The effect of buffered l-ascorbic acid, alone and bound to KMUP-1 or sildenafil, for treating pulmonary arterial hypertension (PAH) is unclear. In this study, the antioxidant capacity of ascorbic acid increased the beneficial effects of KMUP-1 on PAH. KMUP-1A and sildenafil-A (5 mg/kg/d) were administered to hypoxic PAH rats. Pulmonary artery blood pressure, and VEGF, Rho kinase II (ROCK II), eNOS, soluble guanylate cyclase (sGC-α), and protein kinase G expression in lung tissues were measured to link PAH and right ventricular hypertrophy. Hypoxic rats had higher pulmonary artery blood pressure, greater PA medial wall thickness and cardiac weight, and a higher right ventricle/left ventricle + septum [RV/(LV+S)] ratio than normoxic rats. Oral KMUP-1A or sildenafil-A for 21 days in hypoxia prevented the rarefaction of eNOS in immunohistochemistry (IHC), reduced the IHC of VEGF in PAs, restored eNOS/protein kinase G/phosphodiesterase 5A; unaffected sGC-α and inactivated ROCK II expression were also found in lung tissues. In normoxic PA, KMUP-1A/Y27632 (10μM) increased eNOS and reduced ROCK II. ROCK II/reactive oxidative species was increased and eNOS was reduced after long-term hypoxia for 21 days. KMUP-1A or Y27632 blunted ROCK II in short-term hypoxic PA at 24 hours. l-Ascorbic acid + l-sodium ascorbate (40, 80μM) buffer alone directly inhibited the IHC of VEGF in hypoxic PA. Finally, KMUP-1A or sildenafil-A reduced PAH and associated right ventricular hypertrophy.