Vol. 93, Issue 1, 189-194, July 2002
Ambient oxygen regulates epithelial metabolism and nitric
oxide production in the human nose
Hitoshi
Nakano1,
Hiroshi
Ide1,
Toshiyuki
Ogasa1,
Shinobu
Osanai1,
Masanobu
Imada2,
Satoshi
Nonaka2,
Kenjiro
Kikuchi1, and
Jun
Iwamoto3
1 First Department of Medicine,
2 Department of Otorhinolaryngology, and
3 Division of Applied Physiology, School of Nursing,
Asahikawa Medical College, Asahikawa 078-8510, Japan
The effects of ambient O2
tension on epithelial metabolism and nitric oxide (NO) production
(
NO) in the nasal airway were examined in nine
healthy volunteers. Nasal NO, O2
consumption (O2), and CO2
production (CO2) were measured during
normoxia followed by gradual hypoxia from 21 to 0% O2
concentration. Nasal O2,
CO2, and respiratory quotient during
normoxia were determined to be 1.19 ± 0.04 ml/min, 1.60 ± 0.04 ml/min, and 1.35 ± 0.04, respectively. Hypoxia exposure to
the nasal cavity significantly decreased both
CO2 and NO
[CO2: 1.60 ± 0.04 to 0.96 ± 0.03 ml/min (P < 0.01), NO:
530 ± 15 to 336 ± 9 nl/min (P < 0.01)]. NO was reduced commensurately with gradual decline
in O2 tension, and the apparent Km
value for O2 was determined to be 23.0 µM. These results
indicate that the nasal epithelial cells exchange O2 and
CO2 with ambient air in the course of their metabolism and
that nasal epithelial cells can synthesize NO by using ambient O2 as a substrate. We conclude that air-borne
O2 diffuses into the epithelium where it may be utilized
for either cell metabolism or NO synthesis.
airway epithelium; gas exchange
