title: Sildenafil reverses hypoxic pulmonary hypertension in highland and lowland newborn sheep.
abstract: Perinatal exposure to chronic hypoxia induces sustained hypertension and structural and functional changes in the pulmonary vascular bed. We hypothesized that highland newborn lambs (HLNB, 3600 m) have a higher pulmonary arterial pressure (PAP) due in part to a higher activity/expression of phosphodiesterase 5 (PDE5). We administered sildenafil, a PDE5 inhibitor, during basal and hypoxic conditions in the pulmonary hypertensive HLNB and compared them to lowland newborn lambs (LLNB, 580 m). Additionally, we compared the vasodilator responses to sildenafil in isolated small pulmonary arteries and the PDE5 mRNA expression and evaluated the vascular remodeling by histomorphometric analysis in these newborn lambs. Under basal conditions, HLNB had a higher PAP and cardiac output compared with LLNB. Sildenafil decreased the PAP during basal conditions and completely prevented the PAP increase during hypoxia in both groups. HLNB showed a greater contractile capacity and a higher maximal dilation to sildenafil. PDE5 mRNA expression did not show significant differences between HLNB and LLNB. The distal pulmonary arteries showed an increased wall thickness in HLNB. Our results showed that HLNB are more sensitive to sildenafil and therefore could be useful for treatment of pulmonary hypertension in high-altitude neonates.
authors: Program in Pathophysiology, University of Chile, CP 6640871, Santiago, Chile.
authors: Emilio A
authors: EA
authors: Herrera
authors: Germán
authors: G
authors: Ebensperger
authors: Bernardo J
authors: BJ
authors: Krause
authors: Raquel A
authors: RA
authors: Riquelme
authors: Roberto V
authors: RV
authors: Reyes
authors: María
authors: M
authors: Capetillo
authors: Sergio
authors: S
authors: González
authors: Julian T
authors: JT
authors: Parer
authors: Aníbal J
authors: AJ
authors: Llanos
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics; D006976:Hypertension, Pulmonary / Q000188:drug therapy*; D000860:Hypoxia; D008954:Models, Biological; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000187:drug effects / Q000378:metabolism; D011687:Purines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D012756:Sheep; D034561:Sheep, Domestic; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D012333:RNA, Messenger; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate