The clinical significance of exhaled nitric oxide in adolescent smokers

Abstract

Nitric oxide (NO) is known as a marker of eosinophilic inflammation in bronchial asthma. In addition, NO has an antioxidant, bactericidal and cytotoxic effects, relaxes the smooth muscles of the bronchi, improves mucociliary clearance, and is involved in the repair of the mucous membrane of airways. Violation of its metabolism can play an important role in the pathogenesis of chronic respiratory diseases.

The aim is to study the effect of smoking on level of exhaled NO in adolescent smokers.

Methods of Research: 20 adolescent smokers with сhronic bronchitis (CB) (average age is 17.5±0.2 years), 37 healthy adolescent smokers (average age is 15.9±0.2 years), 15 healthy never-smoker adolescents (average age is 15.9±0.4 years) were examined. The concentration of exhaled NO was determined using a Niox Mino. Calculation of the smoking index and the packs/year were made.

Results: The average level of exhaled NO in smokers with CB was 1.4 times less than in healthy adolescent smokers (6.1±0.3 vs 8.8±0.6, p<0.001) and 2 times less than in healthy never-smoker adolescents (8.8±0.6 ppb vs 12.0±0.2 ppb, p<0.001). Low concentrations of exhaled NO in smokers with CB can be caused with direct toxic damage to NO-producing cells, also a decrease in feedback NO-synthase activity due to its high content in tobacco smoke. A relationship was established between the level of exhaled NO and the number of cigarettes smoked per day (r=-0.71; p<0.001), the smoking index (r=-0.71; p<0.001) and the packs/year (r= -0.66; p<0.001).

Conclusion: Exhaled NO may have clinical significance for the diagnosis of chronic inflammatory process and remodeling of the airways in adolescent smokers.