Airway nitric oxide diffusion in asthma: Role in pulmonary function and bronchial responsiveness

Philip E. Silkoff, Jimmie T. Sylvester, Noe Zamel, Solbert Permutt

Research output: Contribution to journalArticle

Abstract

If the nitric oxide (NO) diffusing capacity of the airways (DNO) is the quantity of NO diffusing per unit time into exhaled gas (q̇) divided by the difference between the concentration of NO in the airway wall (C(w)) and lumen, then DNO and C(w) can be estimated from the relationship between exhaled NO concentration and expiratory flow. In 10 normal subjects and 25 asthmatic patients before and after treatment with inhaled beclomethasone, DNO averaged 6.8 ± 1.2, 25.5 ± 3.8, and 22.3 ± 2.7 nl/s/ppb x 10-3, respectively; C(w) averaged 149 ± 31.9, 255.3 ± 46.4, and 108.3 ± 14.3 ppb, respectively; and DNOC(w) (the maximal q̇ from diffusion) averaged 1,020 ± 157.5, 6,512 ± 866, and 2,416 ± 208.5 nl/s x 10-3, respectively. DNO and DNOCw in the asthmatic subjects before and after steroids were greater than in normal subjects (p < 0.0001), but C(w) was not different. Within asthmatic subjects, steroids caused C(w) and DNOC(w) to fall (p < 0.0001), but DNO was unchanged. DNOCw after steroids, presumably reflecting maximal diffusion of constitutive NO, was positively correlated with methacholine PC20 and FEV1/FVC before or after steroids. The increased DNO measured in asthmatic patients may reflect upregulation of nonadrenergic, noncholinergic, NO-producing nerves in airways in compensation for decreased sensitivity of airway smooth muscle to the relaxant effects of endogenous NO.

Original languageEnglish (US)
Pages (from-to)1218-1228
Number of pages11
JournalAmerican journal of respiratory and critical care medicine
Volume161
Issue number4 I
DOIs
StatePublished - Jan 1 2000

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine

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