title: Nitric oxide (NO) in expired air at rest and during exercise.
abstract: Nitric oxide (NO) was analysed in expired air from 27 healthy human subjects. At rest the NO concentration was 10.5 +/- 0.9 ng 1-1 (mean +/- SEM) corresponding to 8.6 +/- 0.7 parts per billion (ppb). The expired NO concentration did not change when the subjects were switched from breathing NO-free tank gas to room air which contained 7.7 ng l-1 NO. Repeated measurements of expired NO with an interval of 1 day showed a mean variation of 2.2 +/- 0.7 ng l-1 NO. The NO concentration in the first portion in the expired tidal volume (44%) was insignificantly higher than in the latter expired portion, 6.9 +/- 1.9 vs. 5.1 +/- 1.0 ng l-1 (n = 5). During moderately heavy exercise on an ergometer bicycle (90 W for women, n = 4, 150 W for men, n = 4) the expired concentration of NO decreased, however because of increased minute ventilation, the expired amount of NO almost doubled (from 111 +/- 12 to 209 +/- 30 ng min-1). The source of the expired NO is not clear and both the airways and the pulmonary circulation may contribute.
authors.affiliation: Department of Clinical Physiology, University Hospital, Uppsala, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Trolin
authors.forename: T
authors.initials: T
authors.lastname: Andén
authors.forename: G
authors.initials: G
authors.lastname: Hedenstierna
mesh_terms: D000328:Adult; D001944:Breath Tests; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis*; D012119:Respiration / Q000502:physiology*; D012146:Rest
chemical_list: D009569:Nitric Oxide