title: Oxygen and carbon isotopic compositions of gases respired by humans.
abstract: Oxygen-isotope fractionation associated with respiration in human individuals at rest is linearly related to the fraction of the O2 utilized in the respiration process. The slope of this relationship is affected by a history of smoking, by vigorous exercise, and by the N2/O2 ratio of the inhaled gas. For patients who suffer anemia-related diseases, the slope of this relationship is directly proportional to their level of hemoglobin. These results introduce a new approach for studying the mechanisms of O2 consumption in human respiration and how they are affected by related diseases.
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125.
authors.forename: S
authors.initials: S
authors.lastname: Epstein
authors.forename: L
authors.initials: L
authors.lastname: Zeiri
mesh_terms: D000328:Adult; D000465:Algorithms; D001944:Breath Tests; D002247:Carbon Isotopes / Q000032:analysis*; D002648:Child; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D010103:Oxygen Isotopes / Q000032:analysis*; D012016:Reference Values; D012119:Respiration
chemical_list: D002247:Carbon Isotopes; D006454:Hemoglobins; D010103:Oxygen Isotopes