Exhaled nitric oxide (NO) concentrations were measured in asthmatic ou
tpatients and in non-smoking and smoking healthy controls. In single e
xhalations, NO showed a peak suggestive of airway origin in both contr
ols and asthmatic patients. The peak NO concentration was higher in as
thmatic patients and lower in smokers than in non-smoking controls (p<
0.05). The findings support a role for NO in the host defence response
in asthma and suggest that NO measurements can discriminate between d
ifferent types of lung disorders.