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Chronically elevated endothelin levels reduce pulmonary vascular reactivity to nitric oxide
Annik Migneault1, Stéphanie Sauvageau, Louis Villeneuve
1Montreal Heart Institute, and University of Montreal, Quebec, Canada.
American Journal of Respiratory and Critical Care Medicine
|December 8, 2004
Summary
Chronic elevated endothelin-1 (ET-1) in plasma impairs pulmonary vasodilator function by increasing reactive oxygen species. This suggests a potential link between hyperendothelinemia and pulmonary hypertension development.
Area of Science:
- Cardiovascular Physiology
- Pulmonary Circulation Research
- Endothelin System Biology
Background:
- Local endothelin (ET) system activation is implicated in pulmonary hypertension.
- The effects of sustained plasma hyperendothelinemia on pulmonary hemodynamics remain unclear.
Purpose of the Study:
- To investigate the impact of chronic plasma hyperendothelinemia on pulmonary circulation in a rat model.
- To assess pulmonary arterial reactivity and vasodilator function under elevated ET-1 conditions.
Main Methods:
- Rats received endothelin-1 (ET-1) via mini-osmotic pumps for 7 or 28 days.
- In vivo hemodynamics and isolated lung pressure-flow relationships were measured.
- Pulmonary artery reactivity was assessed using an isometric myograph.
Main Results:
- Plasma ET-1 levels doubled, and lung tissue ET-1 increased significantly at 7 days, normalizing by 28 days.
- Pulmonary pressure-flow relationships showed an upward shift at 7 days but not at 28 days.
- Vasodilator responses to acetylcholine and sodium nitroprusside were reduced by ~50% after 28 days, linked to reactive oxygen species.
Conclusions:
- Chronic hyperendothelinemia diminishes pulmonary vasodilator reserve, particularly nitric oxide-mediated responses.
- Increased reactive oxygen species production appears central to this impairment.
- Findings suggest a potential clinical relevance for conditions with elevated ET and may inform pulmonary hypertension development research.