Signaling molecules in overcirculation-induced pulmonary hypertension in piglets: effects of sildenafil therapy.
BACKGROUND
The phosphodiesterase type-5 (PDE-5) inhibitor sildenafil has been reported to improve pulmonary arterial hypertension (PAH), but the mechanisms that account for this effect are incompletely understood. Severe pulmonary hypertension has been characterized by defects in a signaling pathway involving angiopoietin-1 and the bone morphogenetic receptor-2 (BMPR-2). We investigated the effects of sildenafil on hemodynamics and signaling molecules in a piglet overcirculation-induced model of early PAH.


RESULTS
Thirty 3-week-old piglets were randomized to placebo or sildenafil therapy 0.75 mg/kg TID after anastomosis of the left subclavian artery to the pulmonary arterial trunk or after a sham operation. Three months later, the animals underwent a hemodynamic evaluation followed by pulmonary tissue sampling for morphometry, immunohistochemistry or radioimmunoassay, and real-time quantitative-polymerase chain reaction. Chronic systemic-to-pulmonary shunting increased pulmonary mRNA for angiopoietin-1, endothelin-1 (ET-1), angiotensin II, inducible nitric oxide synthase, vascular endothelial growth factor, and PDE-5. Pulmonary messenger RNA for BMPR-1A and BMPR-2 decreased. Pulmonary angiotensin II, ET-1, and vascular endothelial growth factor proteins increased. Pulmonary artery pressure increased from 20+/-2 to 33+/-1 mm Hg, and arteriolar medial thickness increased by 91%. The expressions of angiopoietin-1, ET-1, and angiotensin II were tightly correlated to pulmonary hypertension. Sildenafil prevented the increase in pulmonary artery pressure, limited the increase in medial thickness to 41%, and corrected associated biological perturbations except for the angiopoietin-1/BMPR-2 pathway, PDE-5, and angiotensin II.


CONCLUSIONS
Sildenafil partially prevents overcirculation-induced PAH and associated changes in signaling molecules. Angiotensin II, PDE-5, and angiopoietin-1/BMPR-2 signaling may play a dominant role in the early stages of the disease.
Rondelet
Benoit
B
Laboratory of Physiology, Faculty of Medicine, Free University Brussels, Belgium.
Kerbaul
François
F
Van Beneden
Ronald
R
Motte
Sophie
S
Fesler
Pierre
P
Hubloue
Ives
I
Remmelink
Myriam
M
Brimioulle
Serge
S
Salmon
Isabelle
I
Ketelslegers
Jean-Marie
JM
Naeije
Robert
R
D015106:3',5'-Cyclic-GMP Phosphodiesterases; D000714:Anastomosis, Surgical / Q000009:adverse effects; D042683:Angiopoietin-1 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D000804:Angiotensin II / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D001160:Arterioles / Q000648:ultrastructure; D052005:Bone Morphogenetic Protein Receptors, Type I; D052006:Bone Morphogenetic Protein Receptors, Type II; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D004353:Drug Evaluation, Preclinical; D019332:Endothelin-1 / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D006965:Hyperplasia; D006976:Hypertension, Pulmonary / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control*; D023421:Models, Animal; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D010727:Phosphoric Diester Hydrolases / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics; D010879:Piperazines / Q000494:pharmacology / Q000627:therapeutic use*; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011651:Pulmonary Artery / Q000601:surgery; D011687:Purines; D012333:RNA, Messenger / Q000096:biosynthesis; D011897:Random Allocation; D017978:Receptors, Growth Factor / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects*; D000068677:Sildenafil Citrate; D013348:Subclavian Artery / Q000601:surgery; D013450:Sulfones; D034421:Sus scrofa; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics
D042683:Angiopoietin-1; D019332:Endothelin-1; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D012333:RNA, Messenger; D017978:Receptors, Growth Factor; D013450:Sulfones; D042461:Vascular Endothelial Growth Factor A; D000804:Angiotensin II; D000068677:Sildenafil Citrate; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D017346:Protein Serine-Threonine Kinases; D052005:Bone Morphogenetic Protein Receptors, Type I; D052006:Bone Morphogenetic Protein Receptors, Type II; D010727:Phosphoric Diester Hydrolases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5