title: Acute hypoxia increases the cerebral metabolic rate - a magnetic resonance imaging study.
abstract: The aim of the present study was to examine changes in cerebral metabolism by magnetic resonance imaging of healthy subjects during inhalation of 10% O2 hypoxic air. Hypoxic exposure elevates cerebral perfusion, but its effect on energy metabolism has been less investigated. Magnetic resonance imaging techniques were used to measure global cerebral blood flow and the venous oxygen saturation in the sagittal sinus. Global cerebral metabolic rate of oxygen was quantified from cerebral blood flow and arteriovenous oxygen saturation difference. Concentrations of lactate, glutamate, N-acetylaspartate, creatine and phosphocreatine were measured in the visual cortex by magnetic resonance spectroscopy. Twenty-three young healthy males were scanned for 60 min during normoxia, followed by 40 min of breathing hypoxic air. Inhalation of hypoxic air resulted in an increase in cerebral blood flow of 15.5% (p = 0.058), and an increase in cerebral metabolic rate of oxygen of 8.5% (p = 0.035). Cerebral lactate concentration increased by 180.3% ([Formula: see text]), glutamate increased by 4.7% ([Formula: see text]) and creatine and phosphocreatine decreased by 15.2% (p[Formula: see text]). The N-acetylaspartate concentration was unchanged (p = 0.36). In conclusion, acute hypoxia in healthy subjects increased perfusion and metabolic rate, which could represent an increase in neuronal activity. We conclude that marked changes in brain homeostasis occur in the healthy human brain during exposure to acute hypoxia.
authors.affiliation: Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Glostrup, Denmark mark.bitsch.vestergaard@regionh.dk.
authors.forename: Mark B
authors.initials: MB
authors.lastname: Vestergaard
authors.affiliation: Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Glostrup, Denmark.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Lindberg
authors.affiliation: Department of Neuroscience and Pharmacology, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Niels Jacob
authors.initials: NJ
authors.lastname: Aachmann-Andersen
authors.affiliation: Department of Neuroscience and Pharmacology, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Kristian
authors.initials: K
authors.lastname: Lisbjerg
authors.affiliation: Department of Neuroscience and Pharmacology, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Søren Just
authors.initials: SJ
authors.lastname: Christensen
authors.affiliation: Institute of Clinical Medicine, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Ian
authors.initials: I
authors.lastname: Law
authors.affiliation: Department of Neuroscience and Pharmacology, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Rasmussen
authors.affiliation: Department of Neuroscience and Pharmacology, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark Department of Neuroanaesthesia, The Neuroscience Centre, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Niels V
authors.initials: NV
authors.lastname: Olsen
authors.affiliation: Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Glostrup, Denmark Institute of Clinical Medicine, The Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Henrik B W
authors.initials: HBW
authors.lastname: Larsson
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D003401:Creatine / Q000097:blood; D004734:Energy Metabolism / Q000502:physiology*; D018698:Glutamic Acid / Q000097:blood; D006706:Homeostasis; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D019344:Lactic Acid / Q000097:blood; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010100:Oxygen / Q000097:blood; D010477:Perfusion; D055815:Young Adult
chemical_list: D019344:Lactic Acid; D018698:Glutamic Acid; D003401:Creatine; D010100:Oxygen
keywords: Cerebral blood flow; MR spectroscopy; cerebral hemodynamics; energy metabolism; high altitude; magnetic resonance imaging