title: Unchanged cerebral blood flow and oxidative metabolism after acclimatization to high altitude.
abstract: The authors investigated the effect of acclimatization to high altitude on cerebral blood flow and oxidative metabolism at rest and during exercise. Nine healthy, native sea-level residents were studied 3 weeks after arrival at Chacaltaya, Bolivia (5,260 m) and after reacclimatization to sea level. Global cerebral blood flow at rest and during exercise on a bicycle ergometer was measured by the Kety-Schmidt technique. Cerebral metabolic rates of oxygen, glucose, and lactate were calculated by the Fick principle. Cerebral function was assessed by a computer-based measurement of reaction time. At high altitude at rest, arterial carbon dioxide tension, oxygen saturation, and oxygen tension were significantly reduced, and arterial oxygen content was increased because of an increase in hemoglobin concentration. Global cerebral blood flow was similar in the four conditions. Cerebral oxygen delivery and cerebral metabolic rates of oxygen and glucose also remained unchanged, whereas cerebral metabolic rates of lactate increased slightly but nonsignificantly at high altitude during exercise compared with high altitude at rest. Reaction time was unchanged. The data indicate that cerebral blood flow and oxidative metabolism are unaltered after high-altitude acclimatization from sea level, despite marked changes in breathing and other organ functions.
authors.affiliation: Department of Infectious Diseases, National University Hospital Rigshospitalet, Copenhagen, Denmark.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Møller
authors.forename: Olaf B
authors.initials: OB
authors.lastname: Paulson
authors.forename: Tom F
authors.initials: TF
authors.lastname: Hornbein
authors.forename: Wil N J M
authors.initials: WN
authors.lastname: Colier
authors.forename: Anna S
authors.initials: AS
authors.lastname: Paulson
authors.forename: Robert C
authors.initials: RC
authors.lastname: Roach
authors.forename: Søren
authors.initials: S
authors.lastname: Holm
authors.forename: Gitte Moos
authors.initials: GM
authors.lastname: Knudsen
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000328:Adult; D000531:Altitude; D001921:Brain / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D008433:Mathematics; D010100:Oxygen / Q000378:metabolism; D012039:Regional Blood Flow / Q000502:physiology
chemical_list: D019344:Lactic Acid; D005947:Glucose; D010100:Oxygen