title: Regional hypoxic cerebral vasodilation facilitated by diameter changes primarily in anterior versus posterior circulation.
abstract: The inability to quantify cerebral blood flow and changes in macrocirculation cross-sectional area in all brain regions impedes robust insight into hypoxic cerebral blood flow control. We applied four-dimensional flow magnetic resonance imaging to quantify cerebral blood flow (ml • min-1) and cross-sectional area (mm2) simultaneously in 11 arteries. In healthy adults, blood pressure, O2Saturation (SpO2), and end-tidal CO2were measured at baseline and steady-state hypoxia (FiO2= 0.11). We investigated left and right: internal carotid, vertebral, middle, anterior, posterior cerebral arteries, and basilar artery. Hypoxia (SpO2= 80±2%) increased total cerebral blood flow from 621±38 to 742±50 ml • min-1( p < 0.05). Hypoxia increased cerebral blood flow, except in the right posterior cerebral arteries. Hypoxia increased cross-sectional area in the anterior arteries (left and right internal carotid arteries, left and right middle, p < 0.05; left and right anterior p = 0.08) but only the right vertebral artery of the posterior circulation. Nonetheless, relative cerebral blood flow distribution and vascular reactivity (Δ%cerebral blood flow • ΔSpO2-1) were not different between arteries. Collectively, moderate hypoxia: (1) increased cerebral blood flow, but relative distribution remains similar to normoxia, (2) evokes similar vascular reactivity between 11 arteries, and (3) increased cross-sectional area primarily in the anterior arteries. This study provides the first wide-ranging, quantitative, functional and structural data regarding intracranial arteries during hypoxia in humans, highlighting cerebral blood flow regulation of microcirculation and macrocirculation differs between anterior and posterior circulation.
authors.affiliation: 1 Departments of Kinesiology, University of Wisconsin - Madison, WI, USA.
authors.forename: J
authors.initials: J
authors.lastname: Mikhail Kellawan
authors.affiliation: 1 Departments of Kinesiology, University of Wisconsin - Madison, WI, USA.
authors.forename: John W
authors.initials: JW
authors.lastname: Harrell
authors.affiliation: 2 Departments of Medical Physics, University of Wisconsin - Madison, WI, USA.|3 Departments of Radiology, University of Wisconsin - Madison, WI, USA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Roldan-Alzate
authors.affiliation: 2 Departments of Medical Physics, University of Wisconsin - Madison, WI, USA.|3 Departments of Radiology, University of Wisconsin - Madison, WI, USA.
authors.forename: Oliver
authors.initials: O
authors.lastname: Wieben
authors.affiliation: 1 Departments of Kinesiology, University of Wisconsin - Madison, WI, USA.
authors.forename: William G
authors.initials: WG
authors.lastname: Schrage
mesh_terms: D000328:Adult; D020771:Anterior Cerebral Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002245:Carbon Dioxide / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D002534:Hypoxia, Brain / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008833:Microcirculation / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D020769:Posterior Cerebral Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014664:Vasodilation / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: Cerebral blood flow; cerebral blood flow measurement; magnetic resonance imaging; physiology; vascular biology