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Nitric oxide synthases in infants and children with pulmonary hypertension and congenital heart disease

Thomas Hoehn1*, Brigitte Stiller2, Allan R McPhaden3 and Roger M Wadsworth4

Author Affiliations

1 Neonatology and Pediatric Intensive Care Medicine, Department of General Pediatrics, Heinrich-Heine-University, Duesseldorf, Germany

2 Department of Congenital Heart Disease, University Hospital, Freiburg and Department of Pediatric Cardiology, Deutsches Herzzentrum, Berlin, Germany

3 Department of Pathology, Glasgow Royal Infirmary, Glasgow, UK

4 Department of Physiology and Pharmacology, University of Strathclyde, Glasgow, UK

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Respiratory Research 2009, 10:110  doi:10.1186/1465-9921-10-110

Published: 13 November 2009



Nitric oxide is an important regulator of vascular tone in the pulmonary circulation. Surgical correction of congenital heart disease limits pulmonary hypertension to a brief period.


The study has measured expression of endothelial (eNOS), inducible (iNOS), and neuronal nitric oxide synthase (nNOS) in the lungs from biopsies of infants with pulmonary hypertension secondary to cardiac abnormalities (n = 26), compared to a control group who did not have pulmonary or cardiac disease (n = 8).


eNOS, iNOS and nNOS were identified by immunohistochemistry and quantified in specific cell types.

Measurements and main results

Significant increases of eNOS and iNOS staining were found in pulmonary vascular endothelial cells of patients with congenital heart disease compared to control infants. These changes were confined to endothelial cells and not present in other cell types. Patients who strongly expressed eNOS also had strong expression of iNOS.


Upregulation of eNOS and iNOS occurs at an early stage of pulmonary hypertension, and may be a compensatory mechanism limiting the rise in pulmonary artery pressure.