Nitric oxide but not carbon monoxide is continuously released in the human nasal airways

Abstract

Results from different laboratories indicate that nitric oxide (NO) and carbon monoxide (CO) coexist in the human airways both in health and disease. These gases are present in exhaled human breath and high concentrations of NO as well as CO have been reported in the nasal airways. In addition, exhaled CO and NO are increased in patients with airways inflammation. NO and CO were measured simultaneously in orally exhaled air and in air sampled from the nose in 18 healthy subjects using chemiluminescence (for NO) and infrared (for CO) techniques at different fixed flow rates. The acute effects of smoking on airway release of NO and CO were also studied.Nasal NO was detected in all subjects and the concentrations were highly flowdependent (mean ¡ SEM: 236 ¡ 23 and 527 ¡ 49 parts per billion (ppb), at 2 and 0.5 L?min -1 , respectively). In contrast, no evidence of CO release in the nasal airways regardless of sample flow rate was found. In fact, additional experiments indicated a net absorption of CO when low levels of this gas were flushed through the nasal cavity. Nasal CO also remained undetectable after smoking. Both NO (22¡2 ppb) and CO (1.1¡0.1 parts per million) were consistently found in orally exhaled air. CO, but not NO, levels increased acutely after smoking a cigarette.The authors conclude that the patterns of nitric oxide and carbon monoxide release in the airways seem to differ profoundly in healthy subjects. Orally exhaled air contains both nitric oxide and carbon dioxide whereas nasal air contains nitric oxide only.

Relationship Between Exhaled Carbon Monoxide and Airway Hyperresponsiveness in Asthmatic Patients

“…No evidence of CO release in the nasal airways was found. In fact, the authors described an absorption of CO when low levels of this gas were flushed through the nasal cavity and reported that nasal CO also remained undetectable after smoking (28). Moreover, recently it was shown that orally exhaled CO is not flow-dependent, whereas NO is (29).…”

“…It had been suggested that CO was also released in the nose and paranasal sinuses (27). However, a recent study analyzed NO and CO simultaneously in nasal air as well as in orally exhaled air by collecting the airway samples in bags (28). No evidence of CO release in the nasal airways was found.…”

Die Rolle der Luftschadstoffe für die Gesundheit

“…NO findet sich auch im Exhalat, insbesondere aus der Nase (dabei werden bei Gesunden Konzentrationen bis zu 650 μg/ m³ erreicht [93]. NO oxidiert an der Luft rasch zu NO 2 , das deutlich besser wasserlöslich ist [91].…”

Breath Tests in Respiratory and Critical Care Medicine: From Research to Practice in Current Perspectives

“…In adults, NO is produced by the paranasal sinuses and its exhaled concentrations elevate in normal subjects after digested, intravenous, or inhaled L-arginine [51]. In normal subjects, nasal air contains only NO, whereas orally exhaled air contains both NO and CO [52]. A study demonstrated that 2-pentylfuran may be an exhaled biomarker for detection of pulmonary fungal and Streptococcus pneumoniae infections [53].…”