| Assessment of nitric oxide formation during exercise. | |
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MedLine Citation:
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PMID: 10194156 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We measured the end-tidal plateau in exhaled NO concentration (CETNO) by chemiluminescence and calculated the product of V E and CETNO (V NO) in nine healthy subjects at rest and during three intensities of cycling exercise (30%, 60%, and 90% V O2max), two levels of hyperventilation (V E = 42.8 +/- 9.1 L/min and 84.2 +/- 6. 6 L/min), and during breathing of hypoxic gas mixtures (five subjects, FIO2 = 14%) at rest and during exercise at 90% V O2max. Immediately after each trial we also measured exhaled [NO] at constant expiratory flow rates ([NO]CF) of 46 ml/s and 950 ml/s, utilizing added expiratory resistance to increase mouth pressure and close the velum (Silkoff and colleagues, Am. J. Respir. Crit. Care Med. 1997;155:260). CETNO decreased and V NO increased above resting levels with increasing exercise intensity during hyperventilation and during hypoxic exercise (p < 0.05). [NO]CF, measured at either 46 ml/s or 950 ml/s, did not increase under any of the conditions investigated (exercise, hyperventilation, or hypoxia). Venous blood from seven of the subjects was sampled for the measurement of plasma [NO3-]. Resting plasma [NO3-] averaged 42.5 +/- 14.7 micromol/L, with no change during exercise, hyperventilation, or hypoxia. On the basis of these results we conclude that reported increases in V NO do not reflect an exercise-induced augmentation of systemic and/or airway NO production. Rather, the increases in V NO during exercise or hyperventilation are a function of high airflow rates, which reduce the luminal [NO]. This decreases the concentration gradient for NO between the alveolar space and pulmonary capillary blood, which results in a decrease in the fraction of NO taken up by the blood and an increase in the volume of NO recovered in the exhaled air (V NO). |
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Authors:
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C M St Croix; T J Wetter; D F Pegelow; K C Meyer; J A Dempsey |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: American journal of respiratory and critical care medicine Volume: 159 ISSN: 1073-449X ISO Abbreviation: Am. J. Respir. Crit. Care Med. Publication Date: 1999 Apr |
Date Detail:
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Created Date: 1999-05-17 Completed Date: 1999-05-17 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 9421642 Medline TA: Am J Respir Crit Care Med Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1125-33 Citation Subset: AIM; IM |
Affiliation:
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Department of Preventive Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA. cstcroix@facstaff.wisc.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Anoxia / metabolism Breath Tests* Female Humans Hyperventilation / metabolism Male Middle Aged Nitrates / blood Nitric Oxide / biosynthesis* Nitrites / blood Physical Exertion* Pulmonary Ventilation Rest |
| Grant Support | |
ID/Acronym/Agency:
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R01-15469//PHS HHS |
| Chemical | |
Reg. No./Substance:
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0/Nitrates; 0/Nitrites; 10102-43-9/Nitric Oxide |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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