title: Hypoxia depresses nitric oxide output in the human nasal airways.
abstract: OBJECTIVE
  The role of oxygen in the nasal air on nasal nitric oxide (NO) output was studied in 13 adult volunteers.
  
  
  METHODS
  Nasal NO was measured while air containing oxygen (0%-100% in nitrogen) was aspirated through the nasal airway before and after the topical application of xylometazoline.
  
  
  RESULTS
  The mean nasal NO output of the untreated nose was 507.8 +/- 161.9 nL/min (mean +/- SD) when 21% oxygen was aspirated through the nasal cavities in series and remained unaltered by 100% O2 (P = .79). Below 10% oxygen the reduction in nasal NO output correlated positively and significantly with the decrease in oxygen concentration (r2 = 0.14). NO output was 245.2 +/- 153.4 nL/min at 0% oxygen, a significant decline from 21% oxygen (P < .0001). Nasal vasoconstriction induced by xylometazoline and alterations in the blood oxygen content by a maximal breath-holding or breathing 100% oxygen did not alter nasal NO in hypoxia (P = .41).
  
  
  CONCLUSIONS
  Nasal NO output is markedly depressed in hypoxia and is oxygen dependent at concentrations of less than 10%. Approximately 50% of nasally generated NO is produced from oxygen in nasal air or regulated by it.
authors.affiliation: Department of Otolaryngology, St. Michael's Hospital, Ontario, Canada. w.qian@utoronto.ca
authors.forename: J S
authors.initials: JS
authors.lastname: Haight
authors.forename: W
authors.initials: W
authors.lastname: Qian
authors.forename: H
authors.initials: H
authors.lastname: Daya
authors.forename: P
authors.initials: P
authors.lastname: Chalmers
authors.forename: N
authors.initials: N
authors.lastname: Zamel
mesh_terms: D000287:Administration, Topical; D000328:Adult; D000704:Analysis of Variance; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D014663:Nasal Decongestants / Q000008:administration & dosage / Q000494:pharmacology; D009297:Nasal Mucosa / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D009666:Nose / Q000098:blood supply; D010100:Oxygen / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology; D012119:Respiration; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000494:pharmacology; D014665:Vasodilator Agents / Q000378:metabolism*
chemical_list: D007093:Imidazoles; D014663:Nasal Decongestants; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009569:Nitric Oxide; D010100:Oxygen; C009695:xylometazoline