The effect of cigarette smoking on the levels of nitric oxide metabolites in the sputum of patients with acute asthma.

Cigarette smoking may reduce the production of endogenous nitric oxide (NO), which plays an important role in inflammation of the asthmatic airway. NO metabolites in sputum were measured in 11 cigarette smokers and five nonsmokers, all with acute asthma. NO metabolite levels reflected the severity of asthmatic exacerbation, as they were significantly higher in patients with "severe," or "respiratory arrest imminent" asthma than in patients with "mild" to "moderate" asthma. There were no significant differences in sputum NO metabolite levels between smokers and nonsmokers with asthma, nor were any differences observed in NO metabolite levels for relative cigarette pack-years in smokers. These findings suggest that severe airway inflammation outweighs the effect of smoking on NO in the sputum of patients with asthma.