Exhaled nitric oxide and bronchial responsiveness to adenosine 5'-monophosphate in subjects with allergic rhinitis.
OBJECTIVE
To determine differences in exhaled nitric oxide (ENO) between subjects with allergic rhinitis with and without increased responsiveness to direct and indirect bronchoconstrictor agents.


METHODS
Cross-sectional study with the order of challenge tests randomized.


METHODS
Specialist allergy unit in a university hospital.


METHODS
Thirty-eight subjects without asthma with allergic rhinitis and 10 healthy nonatopic control subjects.


RESULTS
Participants were challenged with increasing concentrations of adenosine 5'monophosphate (AMP) and methacholine. ENO was measured with the single-exhalation method. A positive response to both bronchoconstrictor agents was detected in nine subjects with allergic rhinitis, whereas four subjects showed increased responsiveness to AMP but not to methacholine. The geometric mean (range) ENO values were significantly higher in subjects with allergic rhinitis with increased responsiveness to either methacholine or AMP than in subjects with normal responsiveness to both agonists: 51.3 parts per billion (ppb) [22.0 to 108.5 ppb] vs 25.1 ppb (5.7 to 102.9 ppb, respectively; p = 0.007) and healthy control subjects (11.2 ppb [5.0 to 31.9 ppb], p < 0.001). Subjects with allergic rhinitis with normal responsiveness to both agonists also had higher concentrations of ENO than healthy control subjects (p = 0.007). No correlation was found between ENO and either of the provocative concentrations of methacholine or AMP causing a 20% fall in FEV(1).


CONCLUSIONS
In subjects without asthma but with allergic rhinitis, the presence of bronchoconstriction in response to methacholine or AMP is associated with increased ENO concentrations. However, elevated concentrations of ENO are detected even in subjects with allergic rhinitis without airway hyperresponsiveness. These results suggest that the presence of airway hyperresponsiveness is not the only factor that determines the increased NO levels detected in subjects with allergic rhinitis.
Prieto
Luis
L
Sección de Alergología (The NAOMI Project), Universidad de Valencia, Valencia, Spain.
Gutiérrez
Valentina
V
Uixera
Sonia
S
D000249:Adenosine Monophosphate; D000328:Adult; D016535:Bronchial Hyperreactivity / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis* / Q000378:metabolism; D012119:Respiration; D006255:Rhinitis, Allergic, Seasonal / Q000378:metabolism*
D009569:Nitric Oxide; D000249:Adenosine Monophosphate