Mechanisms and applications of acute heat stress on vascular function
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: Coombs, Geoff B.
issued: 2020-10-23T20:33:23Z
issued: 2020
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Passive heat stress shows promise as an effective strategy to reduce the risk of cardiovascular diseases (CVD) as an alternative or adjunct to exercise and/or medication. Improving function of the endothelium is one of the key targets underlying the reduction in CVD risk. Therefore, this thesis aimed to evaluate potential mechanisms of acute heat-related improvement of endothelial function and investigate the effectiveness of heat in selected clinical groups. Endothelial function was measured via the technique of flow-mediated dilation (FMD) and shear stress was estimated using duplex Doppler ultrasound imaging of large arteries. In study #1, we compared forearm vs. whole-body heating in in 12 young, healthy individuals. In addition to elevated shear stress, skin and core temperatures independently increased endothelial function. In study #2, we compared peripheral and cerebrovascular responses to whole-body heating with oral ingestion of an α-1 adrenergic antagonist (Prazosin) or placebo. Although α-1 adrenergic antagonism did not influence hyperthermia-induced reductions in cerebral blood flow or affect post-heating FMD, preliminary trends indicate a potential impact of sympathetic nervous system activity on FMD in the brachial artery. In order to test the effectiveness of passive heating in extremely sedentary individuals in study #3, we measured FMD in 15 participants with cervical spinal cord injuries (SCI) and 15 uninjured controls before and after acute leg heating. There was no change in either brachial or superficial femoral artery FMD in SCI or controls; however, systemically circulating microparticles reflective of endothelial activation were reduced by ~60% after heating in SCI but not controls These reductions in endothelial microparticles were associated with improved shear patterns. Study #4 demonstrated that FMD was not different between older adults who are habitually exposed to passive heat stress (via regular sauna use) compared to those who are n…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/76351
note: i Mechanisms and Applications of Acute Heat Stress on Vascular Function By Geoff B. Coombs BSc, University of Ottawa, 2013 MSc, University of Ottawa, 2016 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE COLLEGE OF GRADUATE STUDIES (Health and Exercise Sciences) THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan) October 2020 © Geoff B. Coombs, 2020 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the dissertation entitled: Mechanisms and Applications of Heat Stress on Vascular Function Submitted by Geoff B. Coombs in partial fulfillment of the requirements of the degree of Doctor of Philosophy. Examining Committee: Dr. Philip Ainslie, School of Health and Exercise Sciences, University of British Columbia Supervisor Dr. Jonathan Little, School of Health and Exercise Sciences, University of British Columbia Supervisory Committee Member Dr. Daniel Gagnon, Département de pharmacologie et physiologie, Université de Montréal Supervisory Committee Member Dr. Christopher West, Faculty of Medicine, University of British Columbia University Examiner Dr. Craig Crandall, Department of Internal Medicine, University of Texas Southwestern External Examiner iii Abstract Passive heat stress shows promise as an effective strategy to reduce the risk of cardiovascular diseases (CVD) as an alternative or adjunct to exercise and/or medication. Improving function of the endothelium is one of the key targets underlying the reduction in CVD risk. Therefore, this thesis aimed to evaluate potential mechanisms of acute heat-related improvement of endothelial function and investigate the effectiveness of heat in selected clinical groups. Endothelial function was measured via the technique of flow-mediated dilation (FMD) and shear stress was estimated using duplex Doppler ultrasound imaging of large arteries. In study #1, we compared forearm vs. whole-b…
has type: Thesis/Dissertation
date issued: 2020-11
is shown at: 10.14288/1.0394808
language: eng
degree discipline: Health and Exercise Sciences
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
type: Text
identifier URI: http://hdl.handle.net/2429/76351