Chronic inhaled nitric oxide: Effects on pulmonary vascular endothelial function and pathology in rats

Christine M. Roos, Deborah U. Frank, Chun Xue, Roger A. Johns, George F. Rich

Research output: Contribution to journalArticlepeer-review

Abstract

Nitric oxide (NO) is a potent endogenous vasodilator produced in endothelial cells. Inhaled NO selectively vasodilates the pulmonary circulation. We determined the effects of chronic inhaled NO on hypoxic pulmonary vascular remodeling and endothelium NO-dependent and -independent vasodilation during normoxic and hypoxic conditions in rats. Rats were exposed to 3 wk of normoxia (N), normoxia + 20 ppm inhaled NO (N + NO), chronic hypoxia with 10% normobaric oxygen (CH), or CH and 20 ppm inhaled NO (CH + NO). Inhaled NO decreased the number of muscular pulmonary arteries, the medial smooth muscle thickness, and the right ventricular hypertrophy associated with chronic hypoxia but had no effect on these parameters in normoxic rats. All groups were evaluated with isolated perfused lungs. The pulmonary artery pressure increased by the same amount in the CH and CH + NO rats compared with N rats. Inhibition of NO synthase with N(ω)-nitro-L- arginine methyl ester (L-NAME) caused treater pulmonary vasoconstriction in CH (19.2 ± 3.7 mmHg) vs. N (7.8 ± 3.0 mmHg) and less in CH + NO (9.1 ± 0.8 mmHg) vs. CH rats. Bradykinin (3 μg) caused greater vasodilation in CH (76 ± 12%) vs. N (29 ± 5%) but significantly less in CH + NO (41 ± 11%) vs. CH rats. Vasodilation with acute inhaled NO (40 ppm) was no different in CH vs. N rats but was lower in CH + NO (19 ± 5%) vs. CH (34 ± 6%) rats. This study demonstrates that chronic inhaled NO attenuates hypoxic pulmonary vascular remodeling. Furthermore, these results suggest that chronic inhaled NO decreases endothelium NO-dependent and -independent vasodilation.

Original languageEnglish (US)
Pages (from-to)252-260
Number of pages9
JournalJournal of applied physiology
Volume80
Issue number1
DOIs
StatePublished - Jan 1996
Externally publishedYes

Keywords

  • chronic hypoxia
  • endothelium-derived relaxing factor
  • nitric oxide synthase
  • normoxia
  • pulmonary hypertension
  • vascular remodeling

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Fingerprint Dive into the research topics of 'Chronic inhaled nitric oxide: Effects on pulmonary vascular endothelial function and pathology in rats'. Together they form a unique fingerprint.

Cite this