1
|
Post TE, Heijn LG, Jordan J, van Gerven JMA. Sensitivity of cognitive function tests to acute hypoxia in healthy subjects: a systematic literature review. Front Physiol 2023; 14:1244279. [PMID: 37885803 PMCID: PMC10598721 DOI: 10.3389/fphys.2023.1244279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 09/25/2023] [Indexed: 10/28/2023] Open
Abstract
Acute exposure to hypoxia can lead to cognitive impairment. Therefore, hypoxia may become a safety concern for occupational or recreational settings at altitude. Cognitive tests are used as a tool to assess the degree to which hypoxia affects cognitive performance. However, so many different cognitive tests are used that comparing studies is challenging. This structured literature evaluation provides an overview of the different cognitive tests used to assess the effects of acute hypoxia on cognitive performance in healthy volunteers. Less frequently used similar cognitive tests were clustered and classified into domains. Subsequently, the different cognitive test clusters were compared for sensitivity to different levels of oxygen saturation. A total of 38 articles complied with the selection criteria, covering 86 different cognitive tests. The tests and clusters showed that the most consistent effects of acute hypoxia were found with the Stroop test (where 42% of studies demonstrated significant abnormalities). The most sensitive clusters were auditory/verbal memory: delayed recognition (83%); evoked potentials (60%); visual/spatial delayed recognition (50%); and sustained attention (47%). Attention tasks were not particularly sensitive to acute hypoxia (impairments in 0%-47% of studies). A significant hypoxia level-response relationship was found for the Stroop test (p = 0.001), as well as three clusters in the executive domain: inhibition (p = 0.034), reasoning/association (p = 0.019), and working memory (p = 0.024). This relationship shows a higher test sensitivity at more severe levels of hypoxia, predominantly below 80% saturation. No significant influence of barometric pressure could be identified in the limited number of studies where this was varied. This review suggests that complex and executive functions are particularly sensitive to hypoxia. Moreover, this literature evaluation provides the first step towards standardization of cognitive testing, which is crucial for a better understanding of the effects of acute hypoxia on cognition.
Collapse
Affiliation(s)
- Titiaan E. Post
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
- Centre for Human Drug Research (CHDR), Leiden, Netherlands
| | - Laurens G. Heijn
- Centre for Human Drug Research (CHDR), Leiden, Netherlands
- Leiden Academic Centre for Drug Research, Leiden, Netherlands
| | - Jens Jordan
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
- Medical Faculty, University of Cologne, Cologne, Germany
| | - Joop M. A. van Gerven
- Centre for Human Drug Research (CHDR), Leiden, Netherlands
- Leiden University Medical Center, Leiden, Netherlands
- Central Committee on Research Involving Human Subjects (CCMO), The Hague, Netherlands
| |
Collapse
|
2
|
Talbot JS, Perkins DR, Dawkins TG, Douglas AJM, Griffiths TD, Richards CT, Owen K, Lord RN, Pugh CJA, Oliver JL, Lloyd RS, Ainslie PN, McManus AM, Stembridge M. Neurovascular coupling and cerebrovascular hemodynamics are modified by exercise training status at different stages of maturation during youth. Am J Physiol Heart Circ Physiol 2023; 325:H510-H521. [PMID: 37450291 PMCID: PMC10538977 DOI: 10.1152/ajpheart.00302.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/10/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
Neurovascular coupling (NVC) is mediated via nitric oxide signaling, which is independently influenced by sex hormones and exercise training. Whether exercise training differentially modifies NVC pre- versus postpuberty, where levels of circulating sex hormones will differ greatly within and between sexes, remains to be determined. Therefore, we investigated the influence of exercise training status on resting intracranial hemodynamics and NVC at different stages of maturation. Posterior and middle cerebral artery velocities (PCAv and MCAv) and pulsatility index (PCAPI and MCAPI) were assessed via transcranial Doppler ultrasound at rest and during visual NVC stimuli. N = 121 exercise-trained (males, n = 32; females, n = 32) and untrained (males, n = 28; females, n = 29) participants were characterized as pre (males, n = 33; females, n = 29)- or post (males, n = 27; females, n = 32)-peak height velocity (PHV). Exercise-trained youth demonstrated higher resting MCAv (P = 0.010). Maturity and training status did not affect the ΔPCAv and ΔMCAv during NVC. However, pre-PHV untrained males (19.4 ± 13.5 vs. 6.8 ± 6.0%; P ≤ 0.001) and females (19.3 ± 10.8 vs. 6.4 ± 7.1%; P ≤ 0.001) had a higher ΔPCAPI during NVC than post-PHV untrained counterparts, whereas the ΔPCAPI was similar in pre- and post-PHV trained youth. Pre-PHV untrained males (19.4 ± 13.5 vs. 7.9 ± 6.0%; P ≤ 0.001) and females (19.3 ± 10.8 vs. 11.1 ± 7.3%; P = 0.016) also had a larger ΔPCAPI than their pre-PHV trained counterparts during NVC, but the ΔPCAPI was similar in trained and untrained post-PHV youth. Collectively, our data indicate that exercise training elevates regional cerebral blood velocities during youth, but training-mediated adaptations in NVC are only attainable during early stages of adolescence. Therefore, childhood provides a unique opportunity for exercise-mediated adaptations in NVC.NEW & NOTEWORTHY We report that the change in cerebral blood velocity during a neurovascular coupling task (NVC) is similar in pre- and postpubertal youth, regardless of exercise-training status. However, prepubertal untrained youth demonstrated a greater increase in cerebral blood pulsatility during the NVC task when compared with their trained counterparts. Our findings highlight that childhood represents a unique opportunity for exercise-mediated adaptations in cerebrovascular hemodynamics during NVC, which may confer long-term benefits in cerebrovascular function.
Collapse
Affiliation(s)
- Jack S Talbot
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
- Centre for Health, Activity and Wellbeing Research, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Dean R Perkins
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Tony G Dawkins
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Andrew J M Douglas
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
- Centre for Health, Activity and Wellbeing Research, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Thomas D Griffiths
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
- Centre for Health, Activity and Wellbeing Research, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Cory T Richards
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
- Centre for Health, Activity and Wellbeing Research, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Kerry Owen
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
- Windsor Clive Primary School, Cardiff, United Kingdom
| | - Rachel N Lord
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
- Centre for Health, Activity and Wellbeing Research, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Christopher J A Pugh
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
- Centre for Health, Activity and Wellbeing Research, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Jon L Oliver
- Youth Physical Development Centre, Cardiff Metropolitan University, Cardiff, United Kingdom
- Sports Performance Research Institute New Zealand, AUT University, Auckland, New Zealand
| | - Rhodri S Lloyd
- Youth Physical Development Centre, Cardiff Metropolitan University, Cardiff, United Kingdom
- Sports Performance Research Institute New Zealand, AUT University, Auckland, New Zealand
- Centre for Sport Science and Human Performance, Waikato Institute of Technology, Waikato, New Zealand
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Ali M McManus
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
- Centre for Health, Activity and Wellbeing Research, Cardiff Metropolitan University, Cardiff, United Kingdom
| |
Collapse
|
3
|
Stacey BS, Hoiland RL, Caldwell HG, Howe CA, Vermeulen T, Tymko MM, Vizcardo‐Galindo GA, Bermudez D, Figueroa‐Mujíica RJ, Gasho C, Tuaillon E, Hirtz C, Lehmann S, Marchi N, Tsukamoto H, Villafuerte FC, Ainslie PN, Bailey DM. Lifelong exposure to high-altitude hypoxia in humans is associated with improved redox homeostasis and structural-functional adaptations of the neurovascular unit. J Physiol 2023; 601:1095-1120. [PMID: 36633375 PMCID: PMC10952731 DOI: 10.1113/jp283362] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 12/20/2022] [Indexed: 01/13/2023] Open
Abstract
High-altitude (HA) hypoxia may alter the structural-functional integrity of the neurovascular unit (NVU). Herein, we compared male lowlanders (n = 9) at sea level (SL) and after 14 days acclimatization to 4300 m (chronic HA) in Cerro de Pasco (CdP), Péru (HA), against sex-, age- and body mass index-matched healthy highlanders (n = 9) native to CdP (lifelong HA). Venous blood was assayed for serum proteins reflecting NVU integrity, in addition to free radicals and nitric oxide (NO). Regional cerebral blood flow (CBF) was examined in conjunction with cerebral substrate delivery, dynamic cerebral autoregulation (dCA), cerebrovascular reactivity to carbon dioxide (CVRCO2 ) and neurovascular coupling (NVC). Psychomotor tests were employed to examine cognitive function. Compared to lowlanders at SL, highlanders exhibited elevated basal plasma and red blood cell NO bioavailability, improved anterior and posterior dCA, elevated anterior CVRCO2 and preserved cerebral substrate delivery, NVC and cognition. In highlanders, S100B, neurofilament light-chain (NF-L) and T-tau were consistently lower and cognition comparable to lowlanders following chronic-HA. These findings highlight novel integrated adaptations towards regulation of the NVU in highlanders that may represent a neuroprotective phenotype underpinning successful adaptation to the lifelong stress of HA hypoxia. KEY POINTS: High-altitude (HA) hypoxia has the potential to alter the structural-functional integrity of the neurovascular unit (NVU) in humans. For the first time, we examined to what extent chronic and lifelong hypoxia impacts multimodal biomarkers reflecting NVU structure and function in lowlanders and native Andean highlanders. Despite lowlanders presenting with a reduction in systemic oxidative-nitrosative stress and maintained cerebral bioenergetics and cerebrovascular function during chronic hypoxia, there was evidence for increased axonal injury and cognitive impairment. Compared to lowlanders at sea level, highlanders exhibited elevated vascular NO bioavailability, improved dynamic regulatory capacity and cerebrovascular reactivity, comparable cerebral substrate delivery and neurovascular coupling, and maintained cognition. Unlike lowlanders following chronic HA, highlanders presented with lower concentrations of S100B, neurofilament light chain and total tau. These findings highlight novel integrated adaptations towards the regulation of the NVU in highlanders that may represent a neuroprotective phenotype underpinning successful adaptation to the lifelong stress of HA hypoxia.
Collapse
Affiliation(s)
- Benjamin S. Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| | - Ryan L. Hoiland
- Department of Anaesthesiology, Pharmacology and Therapeutics, Vancouver General HospitalUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- Department of Cellular and Physiological Sciences, Faculty of MedicineUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Hannah G. Caldwell
- Centre for Heart, Lung and Vascular HealthUniversity of British Columbia‐Okanagan CampusKelownaBritish ColumbiaCanada
| | - Connor A. Howe
- Centre for Heart, Lung and Vascular HealthUniversity of British Columbia‐Okanagan CampusKelownaBritish ColumbiaCanada
| | - Tyler Vermeulen
- Centre for Heart, Lung and Vascular HealthUniversity of British Columbia‐Okanagan CampusKelownaBritish ColumbiaCanada
| | - Michael M. Tymko
- Centre for Heart, Lung and Vascular HealthUniversity of British Columbia‐Okanagan CampusKelownaBritish ColumbiaCanada
- Faculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonAlbertaCanada
- Department of Medicine, Faculty of MedicineUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Gustavo A. Vizcardo‐Galindo
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y FilosofíaUniversidad Peruana Cayetano HerediaLima 31Peru
| | - Daniella Bermudez
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y FilosofíaUniversidad Peruana Cayetano HerediaLima 31Peru
| | - Rómulo J. Figueroa‐Mujíica
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y FilosofíaUniversidad Peruana Cayetano HerediaLima 31Peru
| | - Christopher Gasho
- Division of Pulmonary and Critical CareLoma Linda University School of MedicineLoma LindaCAUSA
| | - Edouard Tuaillon
- Department of Infectious DiseasesUniversity of MontpellierMontpellierFrance
| | - Christophe Hirtz
- LBPC‐PPCUniversité de Montpellier, IRMB CHU de Montpellier, INM INSERMMontpellierFrance
| | - Sylvain Lehmann
- LBPC‐PPCUniversité de Montpellier, IRMB CHU de Montpellier, INM INSERMMontpellierFrance
| | - Nicola Marchi
- Laboratory of Cerebrovascular and Glia Research, Department of Neuroscience, Institute of Functional GenomicsUniversity of MontpellierMontpellierFrance
| | - Hayato Tsukamoto
- Faculty of Sport and Health ScienceRitsumeikan UniversityKusatsuShigaJapan
| | - Francisco C. Villafuerte
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y FilosofíaUniversidad Peruana Cayetano HerediaLima 31Peru
| | - Philip N. Ainslie
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
- Centre for Heart, Lung and Vascular HealthUniversity of British Columbia‐Okanagan CampusKelownaBritish ColumbiaCanada
| | - Damian M. Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| |
Collapse
|
4
|
Wang L, Sang L, Cui Y, Li P, Qiao L, Wang Q, Zhao W, Hu Q, Zhang N, Zhang Y, Qiu M, Chen J. Effects of acute high-altitude exposure on working memory: A functional near-infrared spectroscopy study. Brain Behav 2022; 12:e2776. [PMID: 36321845 PMCID: PMC9759148 DOI: 10.1002/brb3.2776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 07/04/2022] [Accepted: 09/02/2022] [Indexed: 12/23/2022] Open
Abstract
INTRODUCTION Inadequate oxygen availability may lead to impairment of neurocognitive functions. The aim of the present study was to investigate the effect of acute high-altitude exposure on the cerebral hemodynamic response and working memory. METHODS The same subjects performed working memory exercises with forward and backward digit span tasks both under normal oxygen conditions and in large simulated hypobaric hypoxia chambers, and a series of physiological parameters were evaluated. Functional near-infrared spectroscopy was used to measure cerebral blood flow changes in the dorsolateral prefrontal cortex (DLPFC) during the tasks. RESULTS Compared with normoxic conditions, under hypoxic conditions, the heart rate and blood pressure increased, blood oxygen saturation decreased significantly, and the forward task had similar accuracy and response time, while the backward task had lower accuracy and longer response time. Neuroimaging analysis showed increased activation in the DLPFC during the forward task and deactivation during the backward task under hypobaric hypoxia conditions. CONCLUSION Acute high-altitude exposure leads to physiological adaptations. The abnormal hemodynamic responses of the DLPFC to hypoxia at low pressure reveal the disruption of neurocognitive function by acute high-altitude exposure, which compromises complex cognitive functions, and provides a promising application for functional near infrared spectroscopy in the exploration of neural mechanisms in the brain during high-altitude exposure.
Collapse
Affiliation(s)
- Li Wang
- Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Army Medical University, Chongqing, China.,Department of Medical Imaging, College of Biomedical Engineering, Army Medical University, Chongqing, China
| | - Linqiong Sang
- Department of Medical Imaging, College of Biomedical Engineering, Army Medical University, Chongqing, China
| | - Yu Cui
- Department of High Altitude Physiology and Pathology, College of High Altitude Military Medicine, Army Medical University, Chongqing, China
| | - Pengyue Li
- Department of Medical Imaging, College of Biomedical Engineering, Army Medical University, Chongqing, China
| | - Liang Qiao
- Department of Medical Imaging, College of Biomedical Engineering, Army Medical University, Chongqing, China
| | - Qiannan Wang
- Department of Medical Imaging, College of Biomedical Engineering, Army Medical University, Chongqing, China
| | - Wenqi Zhao
- Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Army Medical University, Chongqing, China.,Institute of Medicine and Equipment for High Altitude Region, College of High Altitude Military Medicine, Army Medical University, Chongqing, China
| | - Qiu Hu
- Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Army Medical University, Chongqing, China.,Institute of Medicine and Equipment for High Altitude Region, College of High Altitude Military Medicine, Army Medical University, Chongqing, China
| | - Najing Zhang
- Department of Medical Imaging, College of Biomedical Engineering, Army Medical University, Chongqing, China
| | - Ye Zhang
- Department of Medical Imaging, College of Biomedical Engineering, Army Medical University, Chongqing, China
| | - Mingguo Qiu
- Department of Medical Imaging, College of Biomedical Engineering, Army Medical University, Chongqing, China
| | - Jian Chen
- Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Army Medical University, Chongqing, China.,Institute of Medicine and Equipment for High Altitude Region, College of High Altitude Military Medicine, Army Medical University, Chongqing, China
| |
Collapse
|
5
|
Kennedy CM, Burma JS, Newel KT, Brassard P, Smirl JD. Time course recovery of cerebral blood velocity metrics post aerobic exercise: A systematic review. J Appl Physiol (1985) 2022; 133:471-489. [PMID: 35708702 DOI: 10.1152/japplphysiol.00630.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Currently, the standard approach for restricting exercise prior to cerebrovascular data collection varies widely between 6-24 hours. This universally employed practice is a conservative approach to safeguard physiological alterations that could potentially confound one's study design. Therefore, the purpose of this systematic review was to amalgamate the literature that examines the extent and duration cerebrovascular function is impacted following aerobic exercise measured via transcranial Doppler ultrasound. Further, an exploratory aim was to scrutinize and discuss common biases/limitations in the previous studies to help guide future investigations. Search strategies were developed and imported into PubMed, SPORTDiscus, and Medline databases. A total of 595 records were screened and 35 articles met the inclusion criteria in this review, which included assessments of basic cerebrovascular metrics (n=35), dynamic cerebral autoregulation (dCA; n=9), neurovascular coupling (NVC; n=2); and/or cerebrovascular reactivity (CVR-CO2; n=1) following acute bouts of aerobic exercise. Across all studies, it was found NVC was impacted for 1-hour, basic cerebrovascular parameters and CVR-CO2 parameters 2-hours, and dCA metrics 6-hours post-exercise. Therefore, future studies can provide participants with these evidence-based time restrictions, regarding the minimum time to abstain from exercise prior to data collection. However, it should be noted, other physiological mechanisms could still be altered (e.g., metabolic, hormonal, and/or autonomic influences), despite cerebrovascular function returning to baseline levels. Thus, future investigations should seek to control for as many physiological influences when employing cerebrovascular assessments, immediately following these time restraints. The main limitations/biases were lack of female participants, cardiorespiratory fitness, and consideration for vessel diameter.
Collapse
Affiliation(s)
- Courtney M Kennedy
- Cerebrovascular Concussion Lab, Faculty of Kinesiology, University of Calgary, Alberta, Canada.,Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
| | - Joel S Burma
- Cerebrovascular Concussion Lab, Faculty of Kinesiology, University of Calgary, Alberta, Canada.,Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
| | - Kailey T Newel
- Cerebrovascular Concussion Lab, Faculty of Kinesiology, University of Calgary, Alberta, Canada.,Faculty of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Patrice Brassard
- Department of Kinesiology, Université Laval, Québec, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Québec, Canada
| | - Jonathan David Smirl
- Cerebrovascular Concussion Lab, Faculty of Kinesiology, University of Calgary, Alberta, Canada.,Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
| |
Collapse
|
6
|
Burma JS, Macaulay A, Copeland PV, Khatra O, Bouliane KJ, Smirl JD. Temporal evolution of neurovascular coupling recovery following moderate- and high-intensity exercise. Physiol Rep 2021; 9:e14695. [PMID: 33463899 PMCID: PMC7814491 DOI: 10.14814/phy2.14695] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/24/2020] [Accepted: 12/01/2020] [Indexed: 01/13/2023] Open
Abstract
PURPOSE Studies examining neurovascular coupling (NVC) require participants to refrain from exercise for 12-24 hours. However, there is a paucity of empirical evidence for this restriction. The objectives for this study were to delineate the time-course recovery of NVC metrics following exercise and establish the NVC within- and between-day reliability. METHODS Nine participants completed a complex visual search paradigm to assess NVC via transcranial Doppler ultrasound of the posterior cerebral artery blood velocity (PCA). Measurements were performed prior to and throughout the 8-hour recovery period following three randomized conditions: 45 minutes of moderate-intensity exercise (at 50% heart-rate reserve), 30 minutes high-intensity intervals (10, 1-minute intervals at 85% heart-rate reserve), and control (30 minutes quiet rest). In each condition, baseline measures were collected at 8:00am with serial follow-ups at hours zero, one, two, four, six, and eight. RESULTS Area-under-the-curve and time-to-peak PCA velocity during the visual search were attenuated at hour zero following high-intensity intervals (all p < 0.05); however, these NVC metrics recovered at hour one (all p > 0.13). Conversely, baseline PCA velocity, peak PCA velocity, and the relative percent increase were not different following high-intensity intervals compared to baseline (all p > 0.26). No NVC metrics differed from baseline following both moderate exercise and control conditions (all p > 0.24). The majority of the NVC parameters demonstrated high levels of reliability (intraclass correlation coefficient: >0.90). CONCLUSION Future NVC assessments can take place a minimum of one hour following exercise. Moreover, all metrics did not change across the control condition, therefore future studies using this methodology can reliably quantify NVC between 8:00am and 7:00 pm.
Collapse
Affiliation(s)
- Joel S. Burma
- Concussion Research LaboratoryFaculty of Health and Exercise ScienceUniversity of British ColumbiaKelownaBCCanada
- Sport Injury Prevention Research CentreFaculty of KinesiologyUniversity of CalgaryCalgaryABCanada
- Human Performance LaboratoryFaculty of KinesiologyUniversity of CalgaryCalgaryABCanada
- Hotchkiss Brain InstituteUniversity of CalgaryCalgaryABCanada
- Alberta Children’s Hospital Research InstituteUniversity of CalgaryCalgaryABCanada
- Libin Cardiovascular Institute of AlbertaUniversity of CalgaryABCanada
| | - Alannah Macaulay
- Concussion Research LaboratoryFaculty of Health and Exercise ScienceUniversity of British ColumbiaKelownaBCCanada
- School of Health Sciences, Nuclear MedicineBritish Columbia Institute of TechnologyBurnabyBCCanada
| | - Paige V. Copeland
- Concussion Research LaboratoryFaculty of Health and Exercise ScienceUniversity of British ColumbiaKelownaBCCanada
| | - Omeet Khatra
- Faculty of MedicineUniversity of British ColumbiaVancouverBCCanada
| | - Kevin J. Bouliane
- Concussion Research LaboratoryFaculty of Health and Exercise ScienceUniversity of British ColumbiaKelownaBCCanada
| | - Jonathan D. Smirl
- Concussion Research LaboratoryFaculty of Health and Exercise ScienceUniversity of British ColumbiaKelownaBCCanada
- Sport Injury Prevention Research CentreFaculty of KinesiologyUniversity of CalgaryCalgaryABCanada
- Human Performance LaboratoryFaculty of KinesiologyUniversity of CalgaryCalgaryABCanada
- Hotchkiss Brain InstituteUniversity of CalgaryCalgaryABCanada
- Alberta Children’s Hospital Research InstituteUniversity of CalgaryCalgaryABCanada
- Libin Cardiovascular Institute of AlbertaUniversity of CalgaryABCanada
| |
Collapse
|
7
|
Acute intermittent hypercapnic hypoxia and cerebral neurovascular coupling in males and females. Exp Neurol 2020; 334:113441. [DOI: 10.1016/j.expneurol.2020.113441] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/10/2020] [Accepted: 08/21/2020] [Indexed: 01/01/2023]
|
8
|
Piotrowicz Z, Chalimoniuk M, Płoszczyca K, Czuba M, Langfort J. Exercise-Induced Elevated BDNF Level Does Not Prevent Cognitive Impairment Due to Acute Exposure to Moderate Hypoxia in Well-Trained Athletes. Int J Mol Sci 2020; 21:ijms21155569. [PMID: 32759658 PMCID: PMC7432544 DOI: 10.3390/ijms21155569] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 12/12/2022] Open
Abstract
Exposure to acute hypoxia causes a detrimental effect on the brain which is also manifested by a decrease in the ability to perform psychomotor tasks. Conversely, brain-derived neurotrophic factor (BDNF), whose levels are elevated in response to exercise, is a well-known factor in improving cognitive function. Therefore, the aim of our study was to investigate whether the exercise under hypoxic conditions affects psychomotor performance. For this purpose, 11 healthy young athletes performed a graded cycloergometer exercise test to volitional exhaustion under normoxia and acute mild hypoxia (FiO2 = 14.7%). Before, immediately after exercise and after a period of recovery, choice reaction time (CRT) and number of correct reactions (NCR) in relation to changes in serum BDNF were examined. Additionally, other selected factors which may modify BDNF production, i.e., cortisol (C), nitrite, catecholamines (adrenalin-A, noradrenaline-NA, dopamine-DA, serotonin-5-HT) and endothelin-1 (ET-1), were also measured. Exercise in hypoxic conditions extended CRT by 13.8% (p < 0.01) and decreased NCR (by 11.5%) compared to rest (p < 0.05). During maximal workload, NCR was lower by 9% in hypoxia compared to normoxia (p < 0.05). BDNF increased immediately after exercise in normoxia (by 29.3%; p < 0.01), as well as in hypoxia (by 50.0%; p < 0.001). There were no differences in BDNF between normoxia and hypoxia. Considering the fact that similar levels of BDNF were seen in both conditions but cognitive performance was suppressed in hypoxia, acute elevation of BDNF did not compensate for hypoxia-induced cognition impairment. Moreover, neither potentially negative effects of C nor positive effects of A, DA and NO on the brain were observed in our study.
Collapse
Affiliation(s)
- Zofia Piotrowicz
- Institute of Sport Sciences, The Jerzy Kukuczka Academy of Physical Education, 40-065 Katowice, Poland;
- Correspondence:
| | - Małgorzata Chalimoniuk
- Department of Tourism and Health in Biała Podlaska, The Józef Piłsudski University of Physical Education, 00-968 Warsaw, Poland;
| | - Kamila Płoszczyca
- Department of Kinesiology, Institute of Sport, 01-982 Warsaw, Poland; (K.P.); (M.C.)
| | - Miłosz Czuba
- Department of Kinesiology, Institute of Sport, 01-982 Warsaw, Poland; (K.P.); (M.C.)
- Faculty of Health Sciences, Jan Dlugosz University, 42-200 Czestochowa, Poland
| | - Józef Langfort
- Institute of Sport Sciences, The Jerzy Kukuczka Academy of Physical Education, 40-065 Katowice, Poland;
| |
Collapse
|
9
|
Gibbons TD, Tymko MM, Thomas KN, Wilson LC, Stembridge M, Caldwell HG, Howe CA, Hoiland RL, Akerman AP, Dawkins TG, Patrician A, Coombs GB, Gasho C, Stacey BS, Ainslie PN, Cotter JD. Global REACH 2018: The influence of acute and chronic hypoxia on cerebral haemodynamics and related functional outcomes during cold and heat stress. J Physiol 2020; 598:265-284. [PMID: 31696936 DOI: 10.1113/jp278917] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 10/28/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Thermal and hypoxic stress commonly coexist in environmental, occupational and clinical settings, yet how the brain tolerates these multi-stressor environments is unknown Core cooling by 1.0°C reduced cerebral blood flow (CBF) by 20-30% and cerebral oxygen delivery (CDO2 ) by 12-19% at sea level and high altitude, whereas core heating by 1.5°C did not reliably reduce CBF or CDO2 Oxygen content in arterial blood was fully restored with acclimatisation to 4330 m, but concurrent cold stress reduced CBF and CDO2 Gross indices of cognition were not impaired by any combination of thermal and hypoxic stress despite large reductions in CDO2 Chronic hypoxia renders the brain susceptible to large reductions in oxygen delivery with concurrent cold stress, which might make monitoring core temperature more important in this context ABSTRACT: Real-world settings are composed of multiple environmental stressors, yet the majority of research in environmental physiology investigates these stressors in isolation. The brain is central in both behavioural and physiological responses to threatening stimuli and, given its tight metabolic and haemodynamic requirements, is particularly susceptible to environmental stress. We measured cerebral blood flow (CBF, duplex ultrasound), cerebral oxygen delivery (CDO2 ), oesophageal temperature, and arterial blood gases during exposure to three commonly experienced environmental stressors - heat, cold and hypoxia - in isolation, and in combination. Twelve healthy male subjects (27 ± 11 years) underwent core cooling by 1.0°C and core heating by 1.5°C in randomised order at sea level; acute hypoxia ( P ET , O 2 = 50 mm Hg) was imposed at baseline and at each thermal extreme. Core cooling and heating protocols were repeated after 16 ± 4 days residing at 4330 m to investigate any interactions with high altitude acclimatisation. Cold stress decreased CBF by 20-30% and CDO2 by 12-19% (both P < 0.01) irrespective of altitude, whereas heating did not reliably change either CBF or CDO2 (both P > 0.08). The increases in CBF with acute hypoxia during thermal stress were appropriate to maintain CDO2 at normothermic, normoxic values. Reaction time was faster and slower by 6-9% with heating and cooling, respectively (both P < 0.01), but central (brain) processes were not impaired by any combination of environmental stressors. These findings highlight the powerful influence of core cooling in reducing CDO2 . Despite these large reductions in CDO2 with cold stress, gross indices of cognition remained stable.
Collapse
Affiliation(s)
- T D Gibbons
- School of Physical Education, Sport & Exercise Science, University of Otago, 55/47 Union St W, Dunedin, 9016, New Zealand
| | - M M Tymko
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - K N Thomas
- Department of Surgical Sciences, University of Otago, 201 Great King St, Dunedin, 9016, New Zealand
| | - L C Wilson
- Department of Medicine, University of Otago, 201 Great King St, Dunedin, 9016, New Zealand
| | - M Stembridge
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cyncoed Road, Cardiff, CF23 6XD, UK
| | - H G Caldwell
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - C A Howe
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - R L Hoiland
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - A P Akerman
- Faculty of Health Sciences, University of Ottawa, 125 University St, Ottawa, Ontario, Canada, K1N 6N5
| | - T G Dawkins
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cyncoed Road, Cardiff, CF23 6XD, UK
| | - A Patrician
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - G B Coombs
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - C Gasho
- Division of Pulmonary, Critical Care, Hyperbaric and Sleep Medicine, Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - B S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, UK
| | - P N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - J D Cotter
- School of Physical Education, Sport & Exercise Science, University of Otago, 55/47 Union St W, Dunedin, 9016, New Zealand
| |
Collapse
|
10
|
Lefferts WK, DeBlois JP, Soriano JE, Mann L, Rampuri Z, Herrington B, Thrall S, Bird J, Harman TS, Day TA, Heffernan KS, Brutsaert TD. Preservation of Neurovascular Coupling to Cognitive Activity in Anterior Cerebrovasculature During Incremental Ascent to High Altitude. High Alt Med Biol 2019; 21:20-27. [PMID: 31750741 DOI: 10.1089/ham.2019.0050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Background: High altitude sojourn challenges blood flow regulation in the brain, which may contribute to cognitive dysfunction. Neurovascular coupling (NVC) describes the ability to increase blood flow to working regions of the brain. Effects of high altitude on NVC in frontal regions undergoing cognitive activation are unclear but may be relevant to executive function in high-altitude hypoxia. This study sought to examine the effect of incremental ascent to very high altitude on NVC by measuring anterior cerebral artery (ACA) and middle cerebral artery (MCA) hemodynamic responses to sustained cognitive activity. Materials and Methods: Eight adults (23 ± 7 years, four female) underwent bilateral measurement of ACA and MCA mean velocity and pulsatility index (PI) through transcranial Doppler during a 3-minute Stroop task at 1400, 3440, and 4240 m. Results: Resting MCA and ACA PI decreased with high-altitude hypoxia (p < 0.05). Cognitive activity at all altitudes resulted in similar increases in MCA and ACA mean velocity, and decreases in ACA and MCA PI (p < 0.05 for MCA, p = 0.07 for ACA). No significant altitude-by-Stroop interactions were detected, indicating NVC was stable with increasing altitude. Conclusions: Ascent to very high altitude (4240 m) using an incremental profile that supports partial acclimatization does not appear to disturb (1) increases in cerebral blood velocity and (2) reductions in pulsatility that characterize optimal NVC in frontal regions of the brain during cognitive activity.
Collapse
Affiliation(s)
- Wesley K Lefferts
- Integrative Physiology Laboratory, Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois.,Department of Exercise Science, Syracuse University, Syracuse, New York
| | - Jacob P DeBlois
- Department of Exercise Science, Syracuse University, Syracuse, New York
| | | | - Leah Mann
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Zahrah Rampuri
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | | | - Scott Thrall
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Jordan Bird
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Taylor S Harman
- Department of Exercise Science, Syracuse University, Syracuse, New York
| | - Trevor A Day
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Kevin S Heffernan
- Department of Exercise Science, Syracuse University, Syracuse, New York
| | - Tom D Brutsaert
- Department of Exercise Science, Syracuse University, Syracuse, New York
| |
Collapse
|
11
|
Wollseiffen P, Klein T, Vogt T, Abeln V, Strüder HK, Stuckenschneider T, Sanders M, Claassen JAHR, Askew CD, Carnahan H, Schneider S. Neurocognitive performance is enhanced during short periods of microgravity-Part 2. Physiol Behav 2019; 207:48-54. [PMID: 31029651 DOI: 10.1016/j.physbeh.2019.04.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 04/06/2019] [Accepted: 04/24/2019] [Indexed: 11/29/2022]
Abstract
Previous studies showed a decrease in reaction time during the weightlessness phase of a parabolic flight. This effect was found to be stronger with increasing task complexity and was independent of previous experience of weightlessness as well as anti-nausea medication. Analysis of event related potentials showed a decreased amplitude of the N100-P200 complex in weightlessness but was not able to distinguish a possible effect of task complexity. The present study aimed to extend this previous work, by comparing behavioral (reaction time) and neurological (event related potentials analysis) performance to a simple (oddball) and a complex (mental arithmetic + oddball) task during weightlessness. 28 participants participated in two experiments. 11 participants performed a simple oddball experiment in the 1G and 0G phases of a parabolic flight. 17 participants were presented a complex arithmetic task in combination with an oddball task during the 1G and 0G phases of a parabolic flight. Reaction time as well as event related potentials (ERP) were assessed. Results revealed a reduced reaction time (p < .05) for the complex task during 0G. No gravity effects on reaction time were found for the simple task. In both experiments a reduction of typical ERP amplitudes was noticeable in weightlessness. It is assumed that the weightlessness induced fluid shift to the brain is positively affecting neuro-behavioral performance.
Collapse
Affiliation(s)
- Petra Wollseiffen
- Institute of Movement and Neurosciences, German Sport University Cologne, Germany
| | - Timo Klein
- Institute of Movement and Neurosciences, German Sport University Cologne, Germany; School of Health and Sport Sciences, University of the Sunshine Coast, Maroochydore, Australia
| | - Tobias Vogt
- Institute of Professional Sport Education and Sport Qualifications, German Sport University Cologne, Germany
| | - Vera Abeln
- Institute of Movement and Neurosciences, German Sport University Cologne, Germany
| | - Heiko K Strüder
- Institute of Movement and Neurosciences, German Sport University Cologne, Germany
| | - Tim Stuckenschneider
- Institute of Movement and Neurosciences, German Sport University Cologne, Germany
| | - Marit Sanders
- Department of Geriatric Medicine, Radboud Alzheimer Centre, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Jurgen A H R Claassen
- Department of Geriatric Medicine, Radboud Alzheimer Centre, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Christopher D Askew
- School of Health and Sport Sciences, University of the Sunshine Coast, Maroochydore, Australia
| | - Heather Carnahan
- School of Maritime Studies, Offshore Safety and Survival Centre, Marine Institute, Memorial University of Newfoundland, Canada
| | - Stefan Schneider
- Institute of Movement and Neurosciences, German Sport University Cologne, Germany; School of Health and Sport Sciences, University of the Sunshine Coast, Maroochydore, Australia; School of Maritime Studies, Offshore Safety and Survival Centre, Marine Institute, Memorial University of Newfoundland, Canada.
| |
Collapse
|
12
|
Patrician A, Tymko MM, Caldwell HG, Howe CA, Coombs GB, Stone R, Hamilton A, Hoiland RL, Ainslie PN. The Effect of an Expiratory Resistance Mask with Dead Space on Sleep, Acute Mountain Sickness, Cognition, and Ventilatory Acclimatization in Normobaric Hypoxia. High Alt Med Biol 2019; 20:61-70. [PMID: 30720346 DOI: 10.1089/ham.2018.0074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We examined the hypothesis that an expiratory resistance mask containing a small amount of dead space (ER/DS) would reduce the apnea-hypopnea index (AHI) during sleep, attenuate the severity of acute mountain sickness (AMS), and offset decrements in cognitive function compared with a sham mask. In a double-blinded, randomized, sham-controlled, crossover design, 19 volunteers were exposed to two nights of normobaric hypoxia (FIO2 = 0.125), using a ER/DS mask (3.5 mm restrictive expiratory orifice; 125 mL DS volume) and sham mask (zero-flow resistance; 50 mL DS volume). Cognitive function, AMS, and ventilatory acclimatization were assessed before and after the 12-hour normobaric hypoxia exposure. Polysomnography was conducted during sleep. AHI was reduced using the ER/DS sleep mask compared with the sham (30.1 ± 23.9 events·hr-1 vs. 58.9 ± 34.4 events·hr-1, respectively; p = 0.01). Likewise, oxygen desaturation index and headache severity were reduced (both p < 0.05). There were also benefits on limiting the hypoxia-induced reductions in select measures of reaction speed and attention (p < 0.05). Our study indicates that a simple noninvasive and portable ER/DS mask resulted in reductions (49%) in AHI, and reduced headache severity and aspects of cognitive decline. The field applications of this ER/DS mask should be investigated before recommendations can be made to support its benefit for travel to high altitude.
Collapse
Affiliation(s)
- Alexander Patrician
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Michael M Tymko
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Hannah G Caldwell
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Connor A Howe
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Geoff B Coombs
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Rachel Stone
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Allison Hamilton
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Ryan L Hoiland
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Philip N Ainslie
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| |
Collapse
|
13
|
Leacy JK, Zouboules SM, Mann CR, Peltonen JDB, Saran G, Nysten CE, Nysten HE, Brutsaert TD, O’Halloran KD, Sherpa MT, Day TA. Neurovascular Coupling Remains Intact During Incremental Ascent to High Altitude (4240 m) in Acclimatized Healthy Volunteers. Front Physiol 2018; 9:1691. [PMID: 30546319 PMCID: PMC6279846 DOI: 10.3389/fphys.2018.01691] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 11/09/2018] [Indexed: 12/21/2022] Open
Abstract
Neurovascular coupling (NVC) is the temporal link between neuronal metabolic activity and regional cerebral blood flow (CBF), supporting adequate delivery of nutrients. Exposure to high altitude (HA) imposes several stressors, including hypoxia and hypocapnia, which modulate cerebrovascular tone in an antagonistic fashion. Whether these contrasting stressors and subsequent adaptations affect NVC during incremental ascent to HA is unclear. The aim of this study was to assess whether incremental ascent to HA influences the NVC response. Given that CBF is sensitive to changes in arterial blood gasses, in particular PaCO2, we hypothesized that the vasoconstrictive effect of hypocapnia during ascent would decrease the NVC response. 10 healthy study participants (21.7 ± 1.3 years, 23.57 ± 2.00 kg/m2, mean ± SD) were recruited as part of a research expedition to HA in the Nepal Himalaya. Resting posterior cerebral artery velocity (PCAv), arterial blood gasses (PaO2, SaO2, PaCO2, [HCO3 -], base excess and arterial blood pH) and NVC response of the PCA were measured at four pre-determined locations: Calgary/Kathmandu (1045/1400 m, control), Namche (3440 m), Deboche (3820 m) and Pheriche (4240 m). PCAv was measured using transcranial Doppler ultrasound. Arterial blood draws were taken from the radial artery and analyzed using a portable blood gas/electrolyte analyzer. NVC was determined in response to visual stimulation (VS; Strobe light; 6 Hz; 30 s on/off × 3 trials). The NVC response was averaged across three VS trials at each location. PaO2, SaO2, and PaCO2 were each significantly decreased at 3440, 3820, and 4240 m. No significant differences were found for pH at HA (P > 0.05) due to significant reductions in [HCO3 -] (P < 0.043). As expected, incremental ascent to HA induced a state of hypoxic hypocapnia, whereas normal arterial pH was maintained due to renal compensation. NVC was quantified as the delta (Δ) PCAv from baseline for mean PCAv, peak PCAv and total area under the curve (ΔPCAv tAUC) during VS. No significant differences were found for Δmean, Δpeak or ΔPCAv tAUC between locations (P > 0.05). NVC remains remarkably intact during incremental ascent to HA in healthy acclimatized individuals. Despite the array of superimposed stressors associated with ascent to HA, CBF and NVC regulation may be preserved coincident with arterial pH maintenance during acclimatization.
Collapse
Affiliation(s)
- Jack K. Leacy
- Department of Biology, Mount Royal University, Calgary, AB, Canada
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | | | - Carli R. Mann
- Department of Biology, Mount Royal University, Calgary, AB, Canada
| | | | - Gurkan Saran
- Department of Biology, Mount Royal University, Calgary, AB, Canada
| | | | | | - Tom D. Brutsaert
- School of Education, Syracuse University, Syracuse, NY, United States
| | - Ken D. O’Halloran
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | | | - Trevor A. Day
- Department of Biology, Mount Royal University, Calgary, AB, Canada
| |
Collapse
|