1999 Volume 42 Issue 4 Pages 358-367
Nitric oxide (NO) plays an important role in airway function (previously reported to be responsible for mucociliary activity as a regulator and for bacteriostatic effect) and seems to be implicated in the pathophysiology of several airways diseases.
We measured and examined the exhaled NO concentration in patients (three groups : deviated nasal septum, allergic rhinitis and asthma, and chronic sinusitis) using a chemiluminescence analyzer (CLM-500, Shimazu, Tokyo) both through the mouth and the external nostril. The results showed that in most patients, the measured levels of exhaled NO through the external nostril was higher than when measured through the mouth, thus, indicating that most exhaled NO is derived from the nose and sinus. In comparing the three groups, the exhaled concentration of NO through the external nostril in patients suffering from allergic rhinitis and asthma was significantly higher than that of patients suffering from chronic sinusitis and deviated nasal septum. The changes in exhaled NO concentration in patients before and after surgery were examined periodically for a year. When measured two weeks after surgery, the concentration of exhaled NO showed a decrease in measurements at the time of operation, and gradually increased two weeks after in all cases.
Furthermore, we studied the histological localization of NO in the nasal and sinus mucosa by the immunohistochemical method using antiserums against inducible Nitric Oxide Synthase (iNOS) and endothelial Nitric Oxide Synthase (eNOS). Immunostaining for iNOS was localized to ciliated epitheliums, inflammatory cells and serous parts of glandular cells. For eNOS, immunostaining was localized to vascular endothelium and vascular smooth-muscle cells. Marked staining for iNOS was seen in the apical part of the epithelium in the nasal mucosa obtained from subjects with high concentrations of exhaled NO.
We suggest that NO may be an important inflammatory mediator in nasal diseases, and that the apical part of the nasal epithelium may be one of primary sources of NO production in the upper airways of humans.
