Increased arginase II and decreased NO synthesis in endothelial cells of patients with pulmonary arterial hypertension.


Journal Article

Pulmonary arterial hypertension (PAH), a fatal disease of unknown etiology characterized by impaired regulation of pulmonary hemodynamics and vascular growth, is associated with low levels of pulmonary nitric oxide (NO). Based upon its critical role in mediating vasodilation and cell growth, decrease of NO has been implicated in the pathogenesis of PAH. We evaluated mechanisms for low NO and pulmonary hypertension, including NO synthases (NOS) and factors regulating NOS activity, i.e. the substrate arginine, arginase expression and activity, and endogenous inhibitors of NOS in patients with PAH and healthy controls. PAH lungs had normal NOS I-III expression, but substrate arginine levels were inversely related to pulmonary artery pressures. Activity of arginase, an enzyme that regulates NO biosynthesis through effects on arginine, was higher in PAH serum than in controls, with high-level arginase expression localized by immunostaining to pulmonary endothelial cells. Further, pulmonary artery endothelial cells derived from PAH lung had higher arginase II expression and produced lower NO than control cells in vitro. Thus, substrate availability affects NOS activity and vasodilation, implicating arginase II and alterations in arginine metabolic pathways in the pathophysiology of PAH.

Full Text

Cited Authors

  • Xu, W; Kaneko, FT; Zheng, S; Comhair, SAA; Janocha, AJ; Goggans, T; Thunnissen, FBJM; Farver, C; Hazen, SL; Jennings, C; Dweik, RA; Arroliga, AC; Erzurum, SC

Published Date

  • November 2004

Published In

Volume / Issue

  • 18 / 14

Start / End Page

  • 1746 - 1748

PubMed ID

  • 15364894

Pubmed Central ID

  • 15364894

Electronic International Standard Serial Number (EISSN)

  • 1530-6860

International Standard Serial Number (ISSN)

  • 0892-6638

Digital Object Identifier (DOI)

  • 10.1096/fj.04-2317fje


  • eng