Inhaled mannitol shifts exhaled nitric oxide in opposite directions in asthmatics and healthy subjects.
We investigated if healthy subjects could release NO upon hyperosmolar challenge as a defence mechanism, and whether asthmatics with atopy showed an altered response. A plot of NO output versus flow rate was used to calculate the alveolar level and the NO-flux from the airways. The asthmatics had a higher NO output and this was due to an increased NO-flux from the airways, 86+/-30 nl min(-1) compared with control 21+/-2 nl min(-1) (P<0.05). The alveolar NO levels showed no difference. In response to a dry powder of mannitol the exhaled NO concentration decreased in asthmatics by 37+/-7%, but increased in the control by 9+/-4% (P<0.001). The FEV(1.0) decreased 13+/-2% and airway conductance 42+/-7% in asthmatics and in the controls 2+/-1% and 0+/-7%, respectively (P<0.001). We conclude that asthmatics have an altered response to mannitol challenge in regards to exhaled NO. This may result from down regulation of constitutive NO production as a result of high levels of NO flux from the airways.
Högman
M
M
Department of Medical Sciences, Clinical Physiology, Uppsala University, S-751 85, Uppsala, Sweden. marieann.hogman@medsci.uu.se
Lúdvíksdóttir
D
D
Anderson
S D
SD
George
S
S
Håkansson
L
L
Chan
H K
HK
Meriläinen
P
P
Hedenström
H
H
D000280:Administration, Inhalation; D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D008353:Mannitol / Q000008:administration & dosage / Q000494:pharmacology*; D016210:Methacholine Chloride / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D009994:Osmolar Concentration; D011650:Pulmonary Alveoli / Q000187:drug effects* / Q000378:metabolism; D012129:Respiratory Function Tests
D016210:Methacholine Chloride; D009569:Nitric Oxide; D008353:Mannitol