Physical characteristics and gas composition of nasal air affect nasal nitric oxide release

We studied modulation of release of nitric oxide (NO) into nasal passages b y physical characteristics (airflow, temperature, humidity) or gases (oxyge n, carbon dioxide) in nasal air of humans. Each characteristic or gas in na sal air was changed during voluntary soft palate elevation (to isolate nasa l passages). Increasing airflow through the nose caused incremental increas es in NO release from 211 +/- 23 nl/(min m(-2)) at 1 L/min to 312 +/- 40 nl /(min m(-2)) at 22 L/min (P < 0.001, n = 6). Decreased humidity (dry airflo w, 1-22 L/min) reduced NO release only at the highest airflow rate. Changin g temperature (range 46 to 0 degrees C) had no effect on NO release. Hypoxi a (below 4% O-2,) rapidly and reversibly decreased NO release (200 +/- 40 n l/(min m(-2) at 21% O-2, versus 99 +/- 17 nl/(min m(-2)) at 0% O-2, for 3 m in, (P<0.001, n=5). Carbon dioxide (5%) reduced NO release slightly. We con clude that airflow, reduced humidity, carbon dioxide concentration, and oxy gen concentration modulate NO release into nasal passages. (C)1998 Elsevier Science B.V. All rights reserved.