Cerebrovascular function under extreme environmental hypoxia
department or school: Health and Social Development, Faculty of (Okanagan)
department or school: Health and Exercise Sciences, School of (Okanagan)
data provider: DSpace
degree campus: UBCO
creator: Howe, Connor A.
issued: 2024-09-12T23:31:23Z
issued: 2024
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Hypoxic environments elicit multiple physiological responses in order to maintain sufficient oxygen delivery, and ultimately, maintain function. The brain is particularly susceptible to hypoxic environments as it has essentially no metabolic storage capacity; therefore, it relies on a constant, well titrated supply of oxygen to match metabolic demand. The aim of this thesis was to investigate cerebral blood flow (CBF) regulation under acute and chronic severe environmental hypoxic conditions. Study 1 investigated regional and global patterns of CBF and oxygen delivery (CDO₂) in Andean and Sherpa high-altitude populations and in lowlanders, all residing at an altitude of ~5000m. The findings showed that Sherpa possess a unique CBF phenotype whereby CDO₂ is markedly lower compared to Andeans and lowlanders. Andeans, however, presented with a CBF pattern more similar to lowlanders, but with larger extracranial vessels. In Study 2, it was explored how children and adolescents residing in the highest city in the world (La Rinconada, Peru; 5100m) regulate CBF and whether it differed when compared to Sherpa living at 3800m, and lowlanders living in Wales, UK. The findings revealed that despite Andean children being more hypoxemic, their global CBF was not different compared to the other populations; however, their posterior CBF was ~24% lower. Finally, Study 3 investigated the effect of mild-hypothermia on CBF, CDO₂, cerebral metabolic rate of oxygen (CMRO₂), and blood brain biomarkers in healthy humans during progressive maximal hypercapnic hypoxia, simulating avalanche burial. The main findings were that 1) mild hypothermia reduced CBF during room-air breathing, primarily due to reductions in the partial pressure of arterial CO₂; and 2) CMRO₂ was not different with hypothermia under room-air conditions and during progressive hypercapnic-hypoxia; however, blood brain biomarkers of neuronal and axonal damage, and blood brain barrier permeability were reduced, indicating so…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/89229
note: Cerebrovascular function under extreme environmental hypoxia by Connor A. Howe B.Sc., University of British Columbia Okanagan, 2018 M.Sc., University of British Columbia Okanagan, 2020 A DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Doctor of Philosophy in THE COLLEGE OF GRADUATE STUDIES (Kinesiology) THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan) September 2024 © Connor Howe, 2024 ii The following individuals certify that they have read, and recommend to the College of Graduate Studies for acceptance, the dissertation entitled: Cerebrovascular function under extreme environmental hypoxia submitted by Connor A. Howe in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Kinesiology Examining Committee: Dr. Phil Ainslie, School of Health and Exercise Sciences Supervisor Dr. Jonathan Little, School of Health and Exercise Sciences Supervisory Committee Member Dr. Justin Lawley, Institute of Sports Science Supervisory Committee Member Dr. Chris West, Faculty of Medicine University Examiner Dr. Kate Thomas, Department of Surgical Sciences External Examiner iii Abstract Hypoxic environments elicit multiple physiological responses in order to maintain sufficient oxygen delivery, and ultimately, maintain function. The brain is particularly susceptible to hypoxic environments as it has essentially no metabolic storage capacity; therefore, it relies on a constant, well titrated supply of oxygen to match metabolic demand. The aim of this thesis was to investigate cerebral blood flow (CBF) regulation under acute and chronic severe environmental hypoxic conditions. Study 1 investigated regional and global patterns of CBF and oxygen delivery (CDO2) in Andean and Sherpa high-altitude populations and in lowlanders, all residing at an altitude of ~5000m. The findings showed that Sherpa possess a unique CBF phenotype whereby CDO2 is markedly lower compared to Andeans and lowlanders. Andeans, however, presented with a C…
has type: Thesis/Dissertation
date issued: 2024-09
is shown at: 10.14288/1.0445372
language: eng
degree discipline: Kinesiology
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Ainslie, Philip N., 1974-
type: Text
identifier URI: http://hdl.handle.net/2429/89229