title: Oxygen and nitrogen isotopic fractionations during human respiration.
abstract: Both oxygen and nitrogen isotope compositions (delta18O and delta15N) of exhaled air from 10 individuals were measured. Results show linear relations between isotope variation and the fraction of O2 used during the respiration process. The isotopic influence of physiological parameters such as smoking habits, age, haemoglobin count, oxygen fixation rate or physical exercise was assessed. Among them, only smoking habits do not have any effect on delta18O. Delta15N differences between inhaled and exhaled air may indicate an active (but minor) role for nitrogen during the human respiration process. Nevertheless, nitrogen fractionation is homogenous among all the individuals, which is coherent with the fact that nitrogen metabolism is controlled by the intestinal bacterial activity.
authors.affiliation: BRGM, ANA/ISO, 3, av. Claude-Guillemin, BP 6009, 45060 Orléans cedex 2, France. d.widory@brgm.fr
authors.forename: David
authors.initials: D
authors.lastname: Widory
mesh_terms: D000328:Adult; D000368:Aged; D001944:Breath Tests; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009587:Nitrogen Isotopes / Q000032:analysis / Q000493:pharmacokinetics*; D010103:Oxygen Isotopes / Q000032:analysis / Q000493:pharmacokinetics*; D012016:Reference Values; D012143:Respiratory Physiological Phenomena; D012907:Smoking
chemical_list: D009587:Nitrogen Isotopes; D010103:Oxygen Isotopes