Nitrate in exhaled breath condensate of patients with different airway diseases

There is an increasing interest in the measurement of nitric oxide (NO.) in the airways. NO. is a free radical that reacts rapidly with reactive oxygen species in aqueous solution to form peroxynitrite which can then break down to nitrite (NO2-) and nitrate (NO3-). NO3- is considered a stable oxidative end product of NO. metabolism. The aim of this study was to assay NO3- in exhaled breath condensate (EBC) of normal nonsmoking and smoking subjects, asthmatics, patients with obstructive pulmonary disease (COPD), and patients with community-acquired pneumonia (CAP). EBC was collected using a glass condenser and samples were assayed for NO3- by ion chromatography followed by conductivity measurement. NO3- was detectable in EBC of all subjects. NO3- was elevated in smokers [median (range)] [62.5 (9.6-158.0) muM] and in asthmatics [68.0 (25.8-194.6) muM] compared to controls [9.6 (2.6-119.4) muM; p = 0.003 and p = 0.006, respectively], whereas NO3- was not elevated in COPD patients [24.1 (1.9-337.0) muM]. The concentration of NO3- in patients with CAP [243.4 (26.1-584.5) muM] was higher than that in controls (p = 0.002) and NO3- values decreased after treatment and recovery from illness [40.0 (4.1-167.0) muM, p = 0.009]. This study shows that NO3- is detectable in EBC of healthy subjects and it varies in patients with inflammatory airway diseases. (C) 2002 Elsevier Science (USA). All rights reserved.