TOTAL SPUTUM NITRATE PLUS NITRITE IS RAISED DURING ACUTE PULMONARY INFECTION IN CYSTIC-FIBROSIS

Nitric oxide (NO) can be detected in exhaled gas in human subjects. It is produced by nitric oxide synthase (NOS) and is rapidly metabolized to nitrite and nitrate (NO2/NO3). Exhaled NO is reported to be elevat ed in patients with asthma, bronchiectasis, or upper respiratory tract infection. Recent reports have shown no increase of exhaled NO in sta ble cystic fibrosis (CF). We hypothesized that NOS activity is increas ed in patients with acute pulmonary exacerbation of CF. We therefore m easured exhaled NO and sputum NO2/NO3 in three subject categories: pat ients with acute pulmonary exacerbation of CF, patients with stable CF , and healthy control subjects. Mean +/- SD exhaled NO was significant ly higher in control subjects (8.8 +/- 4.9 ppb) than in both acute (3. 8 +/- 3.9 ppb) and stable (5.0 +/- 2.5 ppb) patients. Sputum NO2/NO3 w as significantly higher in acute patients (774 +/- 307 mu mol/L) when compared with both stable patients (387 +/- 203 mu mol/L) and control (421 +/- 261 mu mol/L) subjects. Sputum NO2/NO3 did not return to norm al in a subgroup of patients assessed after 2 wk of intensive antibiot ic and glucocorticoid treatment. These results confirm that exhaled NO is not a useful measure of airway inflammation in CF. Elevated levels of sputum NO2/NO3 suggest that NOS is activated during acute pulmonar y exacerbations of CF.