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Exhaled NO during graded changes in inhaled oxygen in man
L Schmetterer1, K Strenn, J Kastner
1Department of Clinical Pharmacology, University of Vienna, Austria.
Thorax
|August 1, 1997
Summary
Exhaled nitric oxide (NO) levels in healthy humans increase with higher oxygen levels, indicating greater NO production during hyperoxia. This finding suggests oxygen tension directly influences NO levels in breath.
Area of Science:
- Pulmonary Physiology
- Respiratory Medicine
- Biomedical Research
Background:
- Nitric oxide (NO) is detected in exhaled breath of humans and animals.
- Hypoxia reduces exhaled NO in isolated animal lungs.
Purpose of the Study:
- To investigate the effect of arterial oxygen tension on exhaled NO levels in humans.
- To determine if oxygen levels influence NO production in the respiratory system.
Main Methods:
- A double-blind, randomized crossover study involving 16 healthy subjects.
- Administration of varying oxygen-nitrogen gas mixtures (FiO2 0.1 to 1.0).
- Measurement of exhaled NO using a chemiluminescence detector from end-expiratory breaths.
Main Results:
- A statistically significant, dose-dependent relationship was found between oxygen breathing and exhaled NO levels (p = 0.0012).
- Exhaled NO concentration increased to 39 (4) ppb at FiO2 1.0 (hyperoxia) from a baseline of 31 (3) ppb.
- Exhaled NO decreased to 26 (3) ppb at FiO2 0.1 (hypoxia).
Conclusions:
- Human exhaled NO concentration is significantly influenced by oxygen tension.
- Hyperoxia leads to increased exhaled NO, suggesting enhanced NO production.
- The underlying physiological mechanism for this oxygen-dependent NO modulation requires further investigation.