title: Cerebral blood flow, frontal lobe oxygenation and intra-arterial blood pressure during sprint exercise in normoxia and severe acute hypoxia in humans.
abstract: Cerebral blood flow (CBF) is regulated to secure brain O2delivery while simultaneously avoiding hyperperfusion; however, both requisites may conflict during sprint exercise. To determine whether brain O2delivery or CBF is prioritized, young men performed sprint exercise in normoxia and hypoxia (PIO2= 73 mmHg). During the sprints, cardiac output increased to ∼22 L min-1, mean arterial pressure to ∼131 mmHg and peak systolic blood pressure ranged between 200 and 304 mmHg. Middle-cerebral artery velocity (MCAv) increased to peak values (∼16%) after 7.5 s and decreased to pre-exercise values towards the end of the sprint. When the sprints in normoxia were preceded by a reduced PETCO2, CBF and frontal lobe oxygenation decreased in parallel ( r = 0.93, P < 0.01). In hypoxia, MCAv was increased by 25%, due to a 26% greater vascular conductance, despite 4-6 mmHg lower PaCO2in hypoxia than normoxia. This vasodilation fully accounted for the 22 % lower CaO2in hypoxia, leading to a similar brain O2delivery during the sprints regardless of PIO2. In conclusion, when a conflict exists between preserving brain O2delivery or restraining CBF to avoid potential damage by an elevated perfusion pressure, the priority is given to brain O2delivery.
authors.affiliation: 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|2 Emergency Medicine Department, Insular Universitary Hospital of Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Curtelin
authors.affiliation: 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Morales-Alamo
authors.affiliation: 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Torres-Peralta
authors.affiliation: 4 Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Rasmussen
authors.affiliation: 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: Marcos
authors.initials: M
authors.lastname: Martin-Rincon
authors.affiliation: 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: Mario
authors.initials: M
authors.lastname: Perez-Valera
authors.affiliation: 4 Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Siebenmann
authors.affiliation: 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: Ismael
authors.initials: I
authors.lastname: Pérez-Suárez
authors.affiliation: 5 Department of Physical Education and Sport Sciences, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Evgenia
authors.initials: E
authors.lastname: Cherouveim
authors.affiliation: 6 School of Kinesiology, University of British Columbia, Vancouver, Canada.
authors.forename: A William
authors.initials: AW
authors.lastname: Sheel
authors.affiliation: 4 Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland.
authors.forename: Carsten
authors.initials: C
authors.lastname: Lundby
authors.affiliation: 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.|3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: José Al
authors.initials: JA
authors.lastname: Calbet
mesh_terms: D000328:Adult; D062186:Arterial Pressure / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005625:Frontal Lobe / Q000098:blood supply*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D055815:Young Adult
keywords: Exercise; cerebral blood flow; cerebral haemodynamics; high altitude; hypertension