Nitrate in exhaled breath condensate of patients with different airway diseases.

Abstract 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 (NO 2 − ) and nitrate (NO 3 − ). NO 3 − is considered a stable oxidative end product of NO metabolism. The aim of this study was to assay NO 3 − 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 NO 3 − by ion chromatography followed by conductivity measurement. NO 3 − was detectable in EBC of all subjects. NO 3 − was elevated in smokers [median (range)] [62.5 (9.6–158.0) μM] and in asthmatics [68.0 (25.8–194.6) μM] compared to controls [9.6 (2.6–119.4) μM; p =0.003 and p =0.006, respectively], whereas NO 3 − was not elevated in COPD patients [24.1 (1.9–337.0) μM]. The concentration of NO 3 − in patients with CAP [243.4 (26.1–584.5) μM] was higher than that in controls ( p =0.002) and NO 3 − values decreased after treatment and recovery from illness [40.0 (4.1–167.0) μM, p =0.009]. This study shows that NO 3 − is detectable in EBC of healthy subjects and it varies in patients with inflammatory airway diseases.