Ambient oxygen regulates epithelial metabolism and nitric oxide production in the human nose.
The effects of ambient O(2) tension on epithelial metabolism and nitric oxide (NO) production (VNO) in the nasal airway were examined in nine healthy volunteers. Nasal VNO, O(2) consumption (VO(2)), and CO(2) production (VCO(2)) were measured during normoxia followed by gradual hypoxia from 21 to 0% O(2) concentration. Nasal VO(2), VCO(2), 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 VCO(2) and VNO [VCO(2): 1.60 +/- 0.04 to 0.96 +/- 0.03 ml/min (P < 0.01), VNO: 530 +/- 15 to 336 +/- 9 nl/min (P < 0.01)]. VNO was reduced commensurately with gradual decline in O(2) tension, and the apparent K(m) value for O(2) was determined to be 23.0 microM. These results indicate that the nasal epithelial cells exchange O(2) and CO(2) with ambient air in the course of their metabolism and that nasal epithelial cells can synthesize NO by using ambient O(2) as a substrate. We conclude that air-borne O(2) diffuses into the epithelium where it may be utilized for either cell metabolism or NO synthesis.
Nakano
Hitoshi
H
First Department of Medicine, School of Nursing, Asahikawa Medical College, Japan.
Ide
Hiroshi
H
Ogasa
Toshiyuki
T
Osanai
Shinobu
S
Imada
Masanobu
M
Nonaka
Satoshi
S
Kikuchi
Kenjiro
K
Iwamoto
Jun
J
D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009296:Nasal Cavity / Q000502:physiology; D009297:Nasal Mucosa / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010100:Oxygen / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology
D002245:Carbon Dioxide; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D010100:Oxygen