EFFECTS OF NITRIC-OXIDE ON BLOOD-FLOW AND MUCOCILIARY ACTIVITY IN THEHUMAN NOSE

In an animal model, nitric oxide (NO) has been shown to increase mucoc iliary activity in vivo and ciliary beat frequency in vitro. The aim o f the present study was to investigate the effects of NO on blood flow and mucociliary activity in the human nose. The concentration of NO i n nasal air was measured with a chemiluminescence technique after nebu lizing the NO donor sodium nitroprusside (SNP) at a dose of 3.0 mg int o the nose in six volunteers, and was found to increase by 50.1% +/- 1 0.0% (mean +/- SEM; p <.001) after the SNP challenge. Blood flow measu red by laser Doppler flowmetry increased by 67.3% +/- 15.5% (p <.05) a fter challenge with SNP at 1.0 mg, and by 75.4% +/- 18.5% at 3.0 mg (p <.01; n = 6). The higher dose, which produced no subjective side effe cts, was then used in the mucociliary experiments. The maximum increas e in nasal mucociliary activity was 57.2% +/- 6.7% at 3.0 mg of SNP (n = 5). The findings support the view that NO regulates mucociliary act ivity and blood flow in the human nasal mucosa.