Document Detail

Exhaled nitric oxide is higher both at day and night in subjects with nocturnal asthma.
MedLine Citation:
PMID:  9731024     Owner:  NLM     Status:  MEDLINE    
Nitric oxide in exhaled air is thought to reflect airway inflammation. No data have been reported so far on circadian changes in NO in subjects with nocturnal asthma. To determine whether exhaled NO shows a circadian rhythm inverse to the circadian rhythm in airway obstruction in subjects with nocturnal asthma, we conducted a study involving six healthy controls, eight individuals without nocturnal asthma (4-h to 16-h variation in peak expiratory flow [PEF] <= 15%), and six individuals with nocturnal asthma (4-h to 16-h PEF variation > 15%). Smoking, use of corticosteroids, and recent respiratory infections were excluded. NO concentrations were measured at 12, 16, 20, and 24 h, and at 4, 8, and 12 h of the next day, using the single-breath method. At the same times, FEV1 and PEF were also measured. Mean NO concentrations were significantly higher in subjects with nocturnal asthma than in subjects without nocturnal asthma, and higher in both groups than in healthy controls at all time points. Mean exhaled NO levels over 24 h correlated with the 4-h to 16-h variation in PEF (r = 0.61, p < 0.01). Exhaled NO did not show a significant circadian variation in any of the three groups as assessed with cosinor analysis, in contrast to the FEV1 in both asthma groups (p < 0.05). At 4 h, mean +/- SD NO levels were higher than at 16 h in subjects with nocturnal asthma; at 50 +/- 20 ppb versus 42 +/- 15 ppb (p < 0.05); other measurements at all time points were similar. Differences in NO and FEV1 from 4 h to 16 h did not correlate with one another. We conclude that subjects with nocturnal asthma exhale NO at higher levels both at night and during the day, which may reflect more severe diurnal airway-wall inflammation. A circadian rhythm in exhaled NO was not observed. NO levels did not correspond to the circadian rhythm in airway obstruction. The small increase in NO at 4 h may indicate an aspect of inflammation, but it is not associated with increased nocturnal airway obstruction.
N H ten Hacken; H van der Vaart; T W van der Mark; G H Koëter; D S Postma
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  158     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1998 Sep 
Date Detail:
Created Date:  1998-10-05     Completed Date:  1998-10-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  902-7     Citation Subset:  AIM; IM    
Department of Pulmonology, University Hospital Groningen, Groningen, The Netherlands.
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MeSH Terms
Airway Obstruction / metabolism
Asthma / metabolism*
Bronchial Provocation Tests
Bronchitis / metabolism
Bronchoconstrictor Agents / diagnostic use
Circadian Rhythm / physiology*
Follow-Up Studies
Forced Expiratory Volume / physiology
Methacholine Chloride / diagnostic use
Middle Aged
Nitric Oxide / metabolism*
Peak Expiratory Flow Rate / physiology
Regression Analysis
Respiration / physiology*
Reg. No./Substance:
0/Bronchoconstrictor Agents; 10102-43-9/Nitric Oxide; 62-51-1/Methacholine Chloride

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