Alveolar nitric oxide and effect of deep inspiration during methacholine challenge.
OBJECTIVE
To assess whether the dual anatomic origin of exhaled nitric oxide (NO), namely alveolar and bronchial, could explain the link between exhaled NO and airway responsiveness, and could participate in the bronchodilatory effect of deep inspiration (DI) that may be evidenced during methacholine challenge.


METHODS
Prospective study in a laboratory performing pulmonary function tests of an academic hospital.


METHODS
Patients underwent multiple flow analysis of exhaled NO, allowing calculation of total maximum airway NO flux (J'awno) and NO concentration of expansible compartment (CAno), and received a cumulative methacholine dose of 2,000 microg. DI effect was assessed by continuous measurement of the resistance of respiratory system using the forced oscillation technique before and after DI.


RESULTS
In a first phase involving 23 patients, a positive correlation between log values of J'awno and CAno was demonstrated with the degree of airway responsiveness (percentage of FEV(1) decrease). In a second phase involving 38 patients, only log CAno was correlated with responsiveness, and no significant relationship was demonstrated between J'awno or CAno and the effect of DI. Patients with smaller airways and/or distal airflow limitation exhibited a constrictive response to DI.


CONCLUSIONS
Airway responsiveness is mainly associated with an increase in distal origin of NO output, and no relationship between exhaled NO and the effect of DI was evidenced.
Delclaux
Christophe
C
Unité INSERM U492-Université Paris XII, Faculté de Médecine de Créteil, France. christophe.delclaux@creteil.inserm.fr <christophe.delclaux@creteil.inserm.fr>
Zerah-Lancner
Françoise
F
Mahut
Bruno
B
Ribeil
Stephan
S
Dubois
Armelle
A
Larger
Christian
C
Harf
Alain
A
D000328:Adult; D001944:Breath Tests; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis*; D011650:Pulmonary Alveoli / Q000737:chemistry*
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D009569:Nitric Oxide