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document
Exhaled NO during graded changes in inhaled oxygen in man . BACKGROUND Nitric oxide ( NO ) is present in the exhaled air of animals and humans . In isolated animal lungs the amount of exhaled NO is decreased during hypoxia . A study was undertaken to determine whether changes in arterial oxygen tension affect levels of exhaled NO in humans . METHODS Sixteen healthy subjects were randomised to inhale different gas mixtures of oxygen and nitrogen in a double blind crossover study . Eight gas mixtures of oxygen and nitrogen ( fractional inspired oxygen concentration ( FiO2 ) 0.1 to 1.0 ) were administered . Exhaled NO was measured with a chemiluminescence detector from end expiratory single breath exhalation . RESULTS A dose-dependent change in exhaled NO during graded oxygen breathing was observed ( p = 0.0012 ) . The mean ( SE ) exhaled NO concentration was 31 ( 3 ) ppb at baseline , 39 ( 4 ) ppb at an FiO2 of 1.0 , and 26 ( 3 ) ppb at an FiO2 of 0.1 . CONCLUSIONS The NO concentration in exhaled air in healthy humans is dependent on oxygen tension . Hyperoxia increases the level of exhaled NO , which indicates increased NO production . The mechanism behind this phenomenon remains to be elucidated .
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Intervention_Pharmacological
Nitric oxide
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Intervention_Pharmacological
mixtures of oxygen and nitrogen
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Intervention_Pharmacological
gas mixtures of oxygen and nitrogen
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Outcome_Physical
Exhaled NO
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Outcome_Physical
exhaled NO
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Outcome_Physical
mean ( SE ) exhaled NO concentration
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Outcome_Physical
NO concentration
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Participant_Sex
man .
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Participant_Sample-size
Sixteen