Functional roles of nasal nitric oxide in nasal patency and mucociliary function

The purpose of this study was twofold: (i) to clarify whether it is possible to change the amount of nasal nitric oxide (NO) artificially; and (ii) to confirm that the artificially altered nasal NO has biological properties such as vasodilatation and mucociliary function. We measured nasal NO and nasal airway resistance (NAR) in healthy subjects before and after topical administration of sodium nitroprusside (SNP), an NO donor. We also measured nasal NO and saccharin transport time after administration of SNP or L-N(G)-nitroarginine methylester (L-NAME), a NO synthase inhibitor. In addition, we examined the effect of SNP and L-NAME on nasal NO and saccharin transport time after pretreatment with flutropium bromide (FB), an anticholinergic agent. Administration of SNP elicited increases in nasal NO and NAR in a dose-dependent manner. Nasal NO decreased significantly after topical administration of L-NAME. Saccharin transport time, an indicator of mucociliary function, was shortened after topical administration of SNP and prolonged after administration of L-NAME. Moreover, these phenomena were observed even after pretreatment with FB. These results suggest that artificially altered nasal NO may affect NAR and mucociliary function.