Exchange dynamics of nitric oxide in the human nose

Nasal nitric oxide (NO) exchange dynamics are poorly understood but potenti ally are of importance, inasmuch as they may provide insight into the NO-re lated physiology of the bronchial tree. In healthy human volunteers, NO out put was assessed by isolating the nasal cavity through elevation of the sof t palate and application of tight-fitting nasal olives. Mean NO output was 334 nl/min and was a positive function of gas flow. With the use of a mathe matical model and the introduction of nonzero concentrations of NO, the dif fusing capacity for NO in the nose (D-NO) and the mucosal NO concentration (C-w) were determined. D-NO ranged from 0.52 to 2.98 x 10(-3) nl.s(-1).ppb( -1) and C-w from 1,236 to 8,947 ppb. C-w declined with increasing gas flow, while DNO was constant. NO output declined with luminal hypoxia, particula rly at oxygen tensions <10%. Measurement of nasal DNO and Cw is easy using this method, and the range of intersubject values of Cw raises the possibil ity of interindividual differences in NO-dependent nasal physiology.