title: Regional cerebral blood flow distribution during exercise: influence of oxygen.
abstract: We investigated regional changes in cerebral artery velocity during incremental exercise while breathing normoxia (21% O2), hyperoxia (100% O2) or hypoxia (16% O2) [n=10; randomized cross over design]. Middle cerebral and posterior cerebral arterial velocities (MCAv and PCAv) were measured continuously using transcranial Doppler ultrasound. At rest, only PCAv was reduced (-7%; P=0.016) with hyperoxia. During low-intensity exercise (40% workload maximum [Wmax]) MCAv (+17 cms(-1); +14cms(-1)) and PCAv (+9cms(-1); +14 cms(-1)) were increased above baseline with normoxia and hypoxia, respectively (P<0.05). The absolute increase from rest in MCAv was greater than the increase in PCAv between 40 and 80% Wmax with normoxia; this greater increase in MCAv was also evident at 60% Wmax with hypoxia and hyperoxia. Hyperoxic exercise resulted in larger absolute (+19 cms(-1)) and relative (+40%) increases in PCAv compared with normoxia. Our findings highlight the selective changes in PCAv during hyperoxic incremental exercise.
authors.affiliation: University of British Columbia, Okanagan Campus, 3333 University Way, Kelowna, British Columbia, Canada. kurt.smith@ubc.ca
authors.forename: K J
authors.initials: KJ
authors.lastname: Smith
authors.forename: L E
authors.initials: LE
authors.lastname: Wong
authors.forename: N D
authors.initials: ND
authors.lastname: Eves
authors.forename: G J
authors.initials: GJ
authors.lastname: Koelwyn
authors.forename: J D
authors.initials: JD
authors.lastname: Smirl
authors.forename: C K
authors.initials: CK
authors.lastname: Willie
authors.forename: P N
authors.initials: PN
authors.lastname: Ainslie
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D018592:Cross-Over Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D018496:Hyperoxia / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D020768:Middle Cerebral Artery / Q000502:physiology; D010100:Oxygen / Q000097:blood*; D020769:Posterior Cerebral Artery / Q000502:physiology; D055815:Young Adult
chemical_list: D010100:Oxygen