Journal
FREE RADICAL BIOLOGY AND MEDICINE
Volume 56, Issue -, Pages 28-43Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.freeradbiomed.2012.09.013
Keywords
Endothelin; Pulmonary hypertension; NADPH oxidase; Uncoupled eNOS; Free radicals
Funding
- National Institutes of Health [HL60190, HL67841, HL084739, R21HD057406, 5T32-HL06699]
- Transatlantic Network Development Grant from the Fondation Leducq
- Entelligence Actelion Young Investigator Award for Research Excellence in Pulmonary Hypertension
- American Heart Association National Office
- Southeast Affiliates of the American Heart Association
- Cardiovascular Discovery Institute of Georgia Health Sciences University
- [F32HL103136]
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Pulmonary arterial hypertension (PH) is a fatal disease marked by excessive pulmonary vascular cell proliferation. Patients with idiopathic PH express endothelin-1 (ET-1) at high levels in their lungs. As the activation of both types of ET-1 receptor (ETA and ETB) leads to increased generation of superoxide and hydrogen peroxide, this may contribute to the severe oxidative stress found in PH patients. As a number of pathways may induce oxidative stress, the particular role of ET-1 remains unclear. The aim of this study was to determine whether inhibition of ET-1 signaling could reduce pulmonary oxidative stress and attenuate the progression of disease in rats with occlusive-angioproliferative PH induced by a single dose of SU5416 (200 mg/kg) and subsequent exposure to hypoxia for 21 days. Using this regimen, animals developed severe PH as evidenced by a progressive increase in right-ventricle (RV) peak systolic pressure (RVPSP), severe RV hypertrophy, and pulmonary endothelial and smooth muscle cell proliferation, resulting in plexiform vasculopathy. PH rats also had increased oxidative stress, correlating with endothelial nitric oxide synthase uncoupling and NADPH oxidase activation, leading to enhanced protein nitration and increases in markers of vascular remodeling. Treatment with the combined ET receptor antagonist bosentan (250 mg/kg/day; day 10 to 21) prevented further increase in RVPSP and RV hypertrophy, decreased ETA/ETB protein levels, reduced oxidative stress and protein nitration, and resulted in marked attenuation of pulmonary vascular cell proliferation. We conclude that inhibition of ET-1 signaling significantly attenuates the oxidative and nitrosative stress associated with PH and prevents its progression. (C) 2012 Elsevier Inc. All-rights reserved.
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