Effects of nitric oxide on blood flow and mucociliary activity in the human nose

In an animal model, nitric oxide (NO) has been shown to increase mucociliary activity in vivo and ciliary beat frequency in vitro. The aim of the present study was to investigate the effects of NO on blood flow and mucociliary activity in the human nose. The concentration of NO in nasal air was measured with a chemiluminescence technique after nebulizing the NO donor sodium nitroprusside (SNP) at a dose of 3.0 mg into the nose in six volunteers, and was found to increase by 50.1% +/- 10.0% (mean +/- SEM; p < .001) after the SNP challenge. Blood flow measured by laser Doppler flowmetry increased by 67.3% +/- 15.5% (p < .05) after 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 effects, was then used in the mucociliary experiments. The maximum increase 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 activity and blood flow in the human nasal mucosa.