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Exhaled nitric oxide in isolated pig lungs
G Cremona1, T Higenbottam, M Takao
1Department of Respiratory Physiology, Papworth Hospital, Cambridge, United Kingdom.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|January 1, 1995
Summary
Lung synthesis of nitric oxide (NO) contributes to exhaled NO levels. This study in isolated porcine lungs shows NO production in the lungs, influencing vascular resistance and breath analysis.
Area of Science:
- Physiology
- Pulmonary Medicine
- Biochemistry
Background:
- Endothelium-derived nitric oxide (NO) is crucial for regulating vascular resistance.
- Low concentrations of NO are detected in exhaled breath, but its pulmonary origin is unclear.
Purpose of the Study:
- To investigate whether NO synthesis within the lung contributes to the NO measured in exhaled breath.
- To assess the relationship between pulmonary vascular resistance and exhaled NO levels.
Main Methods:
- Isolated perfused and ventilated porcine lungs were used.
- Chemiluminescence was employed to measure exhaled NO concentrations.
- Pulmonary vascular resistance (PVR) was monitored under various ventilation and perfusion conditions, including hypoxia, vasoconstrictors, acetylcholine, NO synthase inhibition, and blood perfusion.
Main Results:
- Baseline exhaled NO was 5.8 ± 1.8 ppb under normoxic conditions.
- Hypoxic ventilation decreased exhaled NO and increased PVR.
- NO synthase inhibition significantly reduced exhaled NO and increased PVR, while acetylcholine increased exhaled NO and decreased PVR.
- Blood perfusion reduced exhaled NO without altering PVR.
Conclusions:
- Pulmonary NO synthesis contributes to exhaled NO levels.
- Lung NO production influences pulmonary vascular resistance.
- Exhaled NO measurements can reflect pulmonary NO synthesis and vascular status.