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Talbot JS, Perkins DR, Tallon CM, Dawkins TG, Douglas AJM, Beckerleg R, Crofts A, Wright ME, Davies S, Steventon JJ, Murphy K, Lord RN, Pugh CJA, Oliver JL, Lloyd RS, Ainslie PN, McManus AM, Stembridge M. Cerebral blood flow and cerebrovascular reactivity are modified by maturational stage and exercise training status during youth. Exp Physiol 2023; 108:1500-1515. [PMID: 37742137 PMCID: PMC10988468 DOI: 10.1113/ep091279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 09/08/2023] [Indexed: 09/25/2023]
Abstract
NEW FINDINGS What is the central question of this study? Gonadal hormones modulate cerebrovascular function while insulin-like growth factor 1 (IGF-1) facilitates exercise-mediated cerebral angiogenesis; puberty is a critical period of neurodevelopment alongside elevated gonadal hormone and IGF-1 activity: but whether exercise training across puberty enhances cerebrovascular function is unkown. What is the main finding and its importance? Cerebral blood flow is elevated in endurance trained adolescent males when compared to untrained counterparts. However, cerebrovascular reactivity to hypercapnia is faster in trained vs. untrained children, but not adolescents. Exercise-induced improvements in cerebrovascular function are attainable as early as the first decade of life. ABSTRACT Global cerebral blood flow (gCBF) and cerebrovascular reactivity to hypercapnia (CV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) are modulated by gonadal hormone activity, while insulin-like growth factor 1 facilitates exercise-mediated cerebral angiogenesis in adults. Whether critical periods of heightened hormonal and neural development during puberty represent an opportunity to further enhance gCBF andCV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ is currently unknown. Therefore, we used duplex ultrasound to assess gCBF andCV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ in n = 128 adolescents characterised as endurance-exercise trained (males: n = 30, females: n = 36) or untrained (males: n = 29, females: n = 33). Participants were further categorised as pre- (males: n = 35, females: n = 33) or post- (males: n = 24, females: n = 36) peak height velocity (PHV) to determine pubertal or 'maturity' status. Three-factor ANOVA was used to identify main and interaction effects of maturity status, biological sex and training status on gCBF andCV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Data are reported as group means (SD). Pre-PHV youth demonstrated elevated gCBF and slowerCV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ mean response times than post-PHV counterparts (both: P ≤ 0.001). gCBF was only elevated in post-PHV trained males when compared to untrained counterparts (634 (43) vs. 578 (46) ml min-1 ; P = 0.007). However,CV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ mean response time was faster in pre- (72 (20) vs. 95 (29) s; P ≤ 0.001), but not post-PHV (P = 0.721) trained youth when compared to untrained counterparts. Cardiorespiratory fitness was associated with gCBF in post-PHV youth (r2 = 0.19; P ≤ 0.001) andCV R C O 2 ${\mathrm{CV}}{{\mathrm{R}}_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ mean response time in pre-PHV youth (r2 = 0.13; P = 0.014). Higher cardiorespiratory fitness during adolescence can elevate gCBF while exercise training during childhood primes the development of cerebrovascular function, highlighting the importance of exercise training during the early stages of life in shaping the cerebrovascular phenotype.
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Affiliation(s)
- Jack S. Talbot
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Centre for Health, Activity and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
| | - Dean R. Perkins
- Department of Sport ScienceUniversity of InnsbruckInnsbruckAustria
| | - Christine M. Tallon
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaCanada
| | - Tony G. Dawkins
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaCanada
| | - Andrew J. M. Douglas
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Centre for Health, Activity and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
| | - Ryan Beckerleg
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Andrew Crofts
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Melissa E. Wright
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Saajan Davies
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Jessica J. Steventon
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Kevin Murphy
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and AstronomyCardiff UniversityCardiffUK
| | - Rachel N. Lord
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Centre for Health, Activity and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
| | - Christopher J. A. Pugh
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Centre for Health, Activity and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
| | - Jon L. Oliver
- Youth Physical Development CentreCardiff Metropolitan UniversityCardiffUK
- Sports Performance Research Institute New ZealandAUT UniversityAucklandNew Zealand
| | - Rhodri S. Lloyd
- Youth Physical Development CentreCardiff Metropolitan UniversityCardiffUK
- Sports Performance Research Institute New ZealandAUT UniversityAucklandNew Zealand
- Centre for Sport Science and Human PerformanceWaikato Institute of TechnologyWaikatoNew Zealand
| | - Philip N. Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaCanada
| | - Ali M. McManus
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaCanada
| | - Mike Stembridge
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Centre for Health, Activity and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
- Youth Physical Development CentreCardiff Metropolitan UniversityCardiffUK
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2
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Freeberg KA, Craighead DH, Heinbockel TC, Rossman MJ, Jackman RA, Jankowski LR, Ludwig KR, Chonchol M, Bailey EF, Seals DR. Time-efficient, high-resistance inspiratory muscle strength training increases cerebrovascular reactivity in midlife and older adults. Am J Physiol Heart Circ Physiol 2023; 325:H1059-H1068. [PMID: 37682232 PMCID: PMC10908405 DOI: 10.1152/ajpheart.00351.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/22/2023] [Accepted: 09/06/2023] [Indexed: 09/09/2023]
Abstract
Aging is associated with increased risk for cognitive decline and dementia due in part to increases in systolic blood pressure (SBP) and cerebrovascular dysfunction. High-resistance inspiratory muscle strength training (IMST) is a time-efficient, intensive respiratory training protocol (30 resisted inspirations/day) that lowers SBP and improves peripheral vascular function in midlife/older adults with above-normal SBP. However, whether, and by what mechanisms, IMST can improve cerebrovascular function is unknown. We hypothesized that IMST would increase cerebrovascular reactivity to hypercapnia (CVR to CO2), which would coincide with changes to the plasma milieu that improve brain endothelial cell function and enhance cognitive performance (NIH Toolbox). We conducted a 6-wk double-blind, randomized, controlled clinical trial investigating high-resistance IMST [75% maximal inspiratory pressure (PImax); 6×/wk; 4 females, 5 males] vs. low-resistance sham training (15% PImax; 6×/wk; 2 females, 5 males) in midlife/older adults (age 50-79 yr) with initial above-normal SBP. Human brain endothelial cells (HBECs) were exposed to participant plasma and assessed for acetylcholine-stimulated nitric oxide (NO) production. CVR to CO2 increased after high-resistance IMST (pre: 1.38 ± 0.66 cm/s/mmHg; post: 2.31 ± 1.02 cm/s/mmHg, P = 0.020). Acetylcholine-stimulated NO production increased in HBECs exposed to plasma from after vs. before the IMST intervention [pre: 1.49 ± 0.33; post: 1.73 ± 0.35 arbitrary units (AU); P < 0.001]. Episodic memory increased modestly after the IMST intervention (pre: 95 ± 13; post: 103 ± 17 AU; P = 0.045). Cerebrovascular and cognitive function were unchanged in the sham control group. High-resistance IMST may be a promising strategy to improve cerebrovascular and cognitive function in midlife/older adults with above-normal SBP, a population at risk for future cognitive decline and dementia.NEW & NOTEWORTHY Midlife/older adults with above-normal blood pressure are at increased risk of developing cognitive decline and dementia. Our findings suggest that high-resistance inspiratory muscle strength training (IMST), a novel, time-efficient (5-10 min/day) form of physical training, may increase cerebrovascular reactivity to CO2 and episodic memory in midlife/older adults with initial above-normal blood pressure.
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Affiliation(s)
- Kaitlin A Freeberg
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Daniel H Craighead
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Thomas C Heinbockel
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Matthew J Rossman
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Rachel A Jackman
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Lindsey R Jankowski
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Katelyn R Ludwig
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Michel Chonchol
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - E Fiona Bailey
- Department of Physiology, University of Arizona College of Medicine, Tucson, Arizona, United States
| | - Douglas R Seals
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
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3
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Shoemaker LN, Milej D, Sajid A, Mistry J, Lawrence KS, Shoemaker JK. Characterization of cerebral macro- and microvascular hemodynamics during transient hypotension. J Appl Physiol (1985) 2023; 135:717-725. [PMID: 37560766 PMCID: PMC10642516 DOI: 10.1152/japplphysiol.00743.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 06/26/2023] [Accepted: 08/04/2023] [Indexed: 08/11/2023] Open
Abstract
The aim of the current study was to establish the interplay between blood flow patterns within a large cerebral artery and a downstream microvascular segment under conditions of transiently reduced mean arterial pressure (MAP). We report data from nine young, healthy participants (5 women; 26 ± 4 yr) acquired during a 15-s bout of sudden-onset lower body negative pressure (LBNP; -80 mmHg). Simultaneous changes in microvascular cerebral blood flow (CBF) and middle cerebral artery blood velocity (MCAvmean) were captured using diffuse correlation spectroscopy (DCS) and transcranial Doppler ultrasound (TCD), respectively. Brachial blood pressure (finger photoplethysmography) and TCD waveforms were extracted at baseline and during the nadir blood pressure (BP) response to LBNP and analyzed using a modified Windkessel model to calculate indices of cerebrovascular resistance (Ri) and compliance (Ci). Compared with baseline, rapid-onset LBNP decreased MAP by 22 ± 16% and Ri by 14 ± 10% (both P ≤ 0.03). Ci increased (322 ± 298%; P < 0.01) but MCAvmean (-8 ± 16%; P = 0.09) and CBF (-2 ± 3%; P = 0.29) were preserved. The results provide evidence that changes in both vascular resistance and compliance preserve CBF, as indexed by no significant changes in MCAvmean or DCS microvascular flow, during transient hypotension.NEW & NOTEWORTHY To characterize the relationship between cerebrovascular patterns within the large middle cerebral artery (MCA) and a downstream microvascular segment, we used a novel combination of transcranial Doppler ultrasound of the MCA and optical monitoring of a downstream microvascular segment, respectively, under conditions of transiently reduced mean arterial pressure (i.e., lower body negative pressure, -80 mmHg). A rapid increase in vessel compliance accompanied the maintenance of MCA blood velocity and downstream microvascular flow.
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Affiliation(s)
- Leena N Shoemaker
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
- School of Kinesiology, Western University, London, Ontario, Canada
| | - Daniel Milej
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Aleena Sajid
- School of Kinesiology, Western University, London, Ontario, Canada
| | - Jigneshkumar Mistry
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Keith St Lawrence
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - J Kevin Shoemaker
- School of Kinesiology, Western University, London, Ontario, Canada
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
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4
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Shariffi B, Lloyd IN, Cessac ME, Harper JL, Limberg JK. Reproducibility and diurnal variation in middle cerebral artery blood velocity in healthy humans. Exp Physiol 2023; 108:692-705. [PMID: 36951536 PMCID: PMC10148902 DOI: 10.1113/ep090873] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 03/02/2023] [Indexed: 03/24/2023]
Abstract
NEW FINDINGS What is the central question of this study? We sought to establish between-day reproducibility in estimates of middle cerebral artery blood velocity (MCAv) and cerebrovascular reactivity (CVR) in young, healthy male and female adults in tightly controlled experimental conditions. What is the main finding and its importance? Measures of MCAv assessed during morning, afternoon and evening hours are reproducible between days. There is diurnal variation in CVR, with values being highest during the evening compared with the morning. Greater diurnal variation in CVR is associated with more efficient sleep and greater nocturnal blood pressure dipping. These data enhance our understanding of modulators of MCAv and CVR. ABSTRACT Transcranial Doppler (TCD) is used to assess cerebral blood velocity (CBV) and cerebrovascular reactivity (CVR). Assessments of TCD reproducibility are limited, and few include multiple within-day measurements. We sought to establish reproducibility of CBV and CVR in healthy adults during three time periods (morning, afternoon and evening). We hypothesized that CBV and CVR measured at the same time of day are reproducible between days. We also hypothesized that CBV and CVR exhibit diurnal variation, with measurements being higher in the evening compared with morning/afternoon hours. Twelve adults [six male and six female, 27 years (95% CI, 22-31 years)] completed three measurements (morning, afternoon and evening) on two separate days in controlled conditions (e.g., meals, activity and sleep). Middle cerebral artery blood velocity (MCAv, TCD) was measured continuously at rest and during two CVR tests (end-expiratory apnoea and carbogen inhalation). Intraclass correlation coefficients for resting MCAv showed moderate to good reproducibility, which did not differ between morning, afternoon and evening (0.87, 0.56 and 0.67, respectively; P > 0.05). Intraclass correlation coefficients for peak MCAv during apnoea (0.80, 0.46 and 0.65, respectively; P > 0.05) and minute 2 of carbogen inhalation (0.81, 0.74 and 0.73, respectively; P > 0.05) were also not different from morning compared with afternoon/evening. Time of day had no effect on resting MCAv (F = 0.69, P = 0.51, ƞp 2 = 0.06) or the peak response to apnoea (F = 1.00, P = 0.39, ƞp 2 = 0.08); however, peak MCAv during carbogen breathing exhibited diurnal variation, with highest values in the evening (F = 3.41, P = 0.05, ƞp 2 = 0.24). Measures of CBV and CVR assessed via TCD during morning, afternoon and evening hours are reproducible between days. There is diurnal variation in the MCAv response to carbogen exposure, with CVR being highest during evening compared with morning hours.
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Affiliation(s)
- Brian Shariffi
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Iman N. Lloyd
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Mikala E. Cessac
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Jennifer L. Harper
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | - Jacqueline K. Limberg
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
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5
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Ogoh S, Watanabe H, Saito S, Fisher JP, Iwamoto E. Can Alterations in Cerebrovascular CO 2 Reactivity Be Identified Using Transfer Function Analysis without the Requirement for Carbon Dioxide Inhalation? J Clin Med 2023; 12:jcm12062441. [PMID: 36983441 PMCID: PMC10051076 DOI: 10.3390/jcm12062441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/09/2023] [Accepted: 03/21/2023] [Indexed: 03/30/2023] Open
Abstract
The present study aimed to examine the validity of a novel method to assess cerebrovascular carbon dioxide (CO2) reactivity (CVR) that does not require a CO2 inhalation challenge, e.g., for use in patients with respiratory disease or the elderly, etc. In twenty-one healthy participants, CVR responses to orthostatic stress (50° head-up tilt, HUT) were assessed using two methods: (1) the traditional CO2 inhalation method, and (2) transfer function analysis (TFA) between middle cerebral artery blood velocity (MCA V) and predicted arterial partial pressure of CO2 (PaCO2) during spontaneous respiration. During HUT, MCA V steady-state (i.e., magnitude) and MCA V onset (i.e., time constant) responses to CO2 inhalation were decreased (p < 0.001) and increased (p = 0.001), respectively, indicative of attenuated CVR. In contrast, TFA gain in the very low-frequency range (VLF, 0.005-0.024 Hz) was unchanged, while the TFA phase in the VLF approached zero during HUT (-0.38 ± 0.59 vs. 0.31 ± 0.78 radians, supine vs. HUT; p = 0.003), indicative of a shorter time (i.e., improved) response of CVR. These findings indicate that CVR metrics determined by TFA without a CO2 inhalation do not track HUT-evoked reductions in CVR identified using CO2 inhalation, suggesting that enhanced cerebral blood flow response to a change in CO2 using CO2 inhalation is necessary to assess CVR adequately.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe 350-8585, Japan
- Neurovascular Research Laboratory, University of South Wales, Pontypridd CF37 1DL, UK
| | - Hironori Watanabe
- Department of Biomedical Engineering, Toyo University, Kawagoe 350-8585, Japan
| | - Shotaro Saito
- Department of Biomedical Engineering, Toyo University, Kawagoe 350-8585, Japan
| | - James P Fisher
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand
| | - Erika Iwamoto
- School of Health Sciences, Sapporo Medical University, Sapporo 060-8556, Japan
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6
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Fujimoto T, Dobashi K, Fujii N, Matsutake R, Nishiyasu T. Hypocapnia attenuates local skin thermal perception to innocuous warm and cool stimuli in normothermic resting humans. Am J Physiol Regul Integr Comp Physiol 2023; 324:R120-R127. [PMID: 36534588 DOI: 10.1152/ajpregu.00126.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
When one is exposed to a stressful situation in their daily life, a common response is hyperventilation. Although the physiological significance of stress-induced hyperventilation remains uncertain, this response may blunt perception of the stress-inducing stimulus. This study examined the effects of voluntary hyperventilation and resultant hypocapnia on the local skin thermal detection threshold in normothermic resting humans. Local skin thermal detection thresholds were measured in 15 young adults (three females) under three breathing conditions: 1) spontaneous breathing (Control trial), 2) voluntary hypocapnic hyperventilation (HH trial), and 3) voluntary normocapnic hyperventilation (NH trial). Local skin thermal detection thresholds were measured using thermostimulators containing a Peltier element that were attached to the forearm and forehead. The temperature of the probe was initially equilibrated to the skin temperature, then gradually increased or decreased at a constant rate (±0.1 °C/s) until the participants felt warmth or coolness. The difference between the initial skin temperature and the local skin temperature at which the participant noticed warmth/coolness was assessed as an index of the local skin warm/cool detection threshold. Local detection of warm and cool stimuli did not differ between the Control and NH trials, but it was blunted in the HH trial as compared with the Control and NH trials, except for detection of warm stimuli on the forearm. These findings suggest that hyperventilation-induced hypocapnia, not hyperventilation per se, attenuates local skin thermal perception, though changes in responses to warm stimuli may not be clearly perceived at some skin areas (e.g., forearm).
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Affiliation(s)
- Tomomi Fujimoto
- Department of Health and Sports, Niigata University of Health and Welfare, Niigata, Japan.,Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Kohei Dobashi
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.,Faculty of Education, Hokkaido University of Education, Asahikawa, Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.,Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba, Tsukuba, Japan
| | - Ryoko Matsutake
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.,Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba, Tsukuba, Japan
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7
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Validity of transcranial Doppler ultrasonography-determined dynamic cerebral autoregulation estimated using transfer function analysis. J Clin Monit Comput 2022; 36:1711-1721. [PMID: 35075510 DOI: 10.1007/s10877-022-00817-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
Abstract
Transcranial Doppler ultrasonography (TCD) is used widely to evaluate dynamic cerebral autoregulation (dCA). However, the validity of TCD-determined dCA remains unknown because TCD is only capable of measuring blood velocity and thus only provides an index as opposed to true blood flow. To test the validity of TCD-determined dCA, in nine healthy subjects, dCA was evaluated by transfer function analysis (TFA) using cerebral blood flow (CBF) or TCD-measured cerebral blood velocity during a perturbation that induces reductions in TCD-determined dCA, lower body negative pressure (LBNP) at two different stages: LBNP - 15 mmHg and - 50 mmHg. Internal carotid artery blood flow (ICA Q) was assessed as an index of CBF using duplex Doppler ultrasound. The TFA low frequency (LF) normalized gain (ngain) calculated using ICA Q increased during LBNP at - 50 mmHg (LBNP50) from rest (P = 0.005) and LBNP at - 15 mmHg (LBNP15) (P = 0.015), indicating an impaired dCA. These responses were the same as those obtained using TCD-measured cerebral blood velocity (from rest and LBNP15; P = 0.001 and P = 0.015). In addition, the ICA Q-determined TFA LF ngain from rest to LBNP50 was significantly correlated with TCD-determined TFA LF ngain (r = 0.460, P = 0.016) despite a low intraclass correlation coefficient. Moreover, in the Bland-Altman analysis, the difference in the TFA LF ngains determined by blood flow and velocity was within the margin of error, indicating that the two measurement methods can be interpreted as equivalent. These findings suggest that TCD-determined dCA can be representative of actual dCA evaluated with CBF.
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8
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Zeller NP, Miller KB, Zea RD, Howery AJ, Labrecque L, Aaron SE, Brassard P, Billinger SA, Barnes JN. Sex-specific effects of cardiorespiratory fitness on age-related differences in cerebral hemodynamics. J Appl Physiol (1985) 2022; 132:1310-1317. [PMID: 35446599 PMCID: PMC9126221 DOI: 10.1152/japplphysiol.00782.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There is a positive association between cardiorespiratory fitness and cognitive health, but the interaction between cardiorespiratory fitness and aging on cerebral hemodynamics is unclear. These potential interactions are further influenced by sex differences. The purpose of this study was to determine the sex-specific relationships between cardiorespiratory fitness, age, and cerebral hemodynamics in humans. Measurements of unilateral middle cerebral artery blood velocity (MCAv) and cerebral pulsatility index obtained using transcranial Doppler ultrasound and cardiorespiratory fitness [maximal oxygen consumption (V̇o2max)] obtained from maximal incremental exercise tests were retrieved from study records at three institutions. A total of 153 healthy participants were included in the analysis (age = 42 ± 20 yr, range = 18-83 yr). There was no association between V̇o2max and MCAv in all participants (P = 0.20). The association between V̇o2max and MCAv was positive in women, but no longer significant after age adjustment (univariate: P = 0.01; age-adjusted: P = 0.45). In addition, there was no association between V̇o2max and MCAv in men (univariate: P = 0.25, age-adjusted: P = 0.57). For V̇o2max and cerebral pulsatility index, there were significant negative associations in all participants (P < 0.001), in men (P < 0.001) and women (P < 0.001). This association remained significant when adjusting for age in women only (P = 0.03). In summary, higher cardiorespiratory fitness was associated with a lower cerebral pulsatility index in all participants, and the significance remained only in women when adjusting for age. Future studies are needed to determine the sex-specific impact of cardiorespiratory fitness improvements on cerebrovascular health.NEW & NOTEWORTHY We present data pooled from three institutions to study the impact of age, sex, and cardiorespiratory fitness on cerebral hemodynamics. Cardiorespiratory fitness was positively associated with middle cerebral artery blood velocity in women, but not in men. Furthermore, cardiorespiratory fitness was inversely associated with cerebral pulsatility index in both men and women, which remained significant in women when adjusting for age. These data suggest a sex-specific impact of cardiorespiratory fitness on resting cerebral hemodynamics.
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Affiliation(s)
- Niklaus P Zeller
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Kathleen B Miller
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Ryan D Zea
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Anna J Howery
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut, Universitaire de Cardiologie et de Pneumologie de Québec-Université Laval, Quebec City, Québec, Canada
| | - Stacey E Aaron
- Department of Physical Therapy, Rehabilitation Science and Athletic Training, University of Kansas Medical Center, Kansas City, Kansas
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut, Universitaire de Cardiologie et de Pneumologie de Québec-Université Laval, Quebec City, Québec, Canada
| | - Sandra A Billinger
- Department of Physical Therapy, Rehabilitation Science and Athletic Training, University of Kansas Medical Center, Kansas City, Kansas.,University of Kansas Alzheimer's Disease Research Center, Fairway, Kansas
| | - Jill N Barnes
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
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Moncion K, Allison EY, Al-Khazraji BK, MacDonald MJ, Roig M, Tang A. What are the effects of acute exercise and exercise training on cerebrovascular hemodynamics following stroke? A systematic review and meta-analysis. J Appl Physiol (1985) 2022; 132:1379-1393. [PMID: 35482325 DOI: 10.1152/japplphysiol.00872.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Limited data exist regarding the effects of acute exercise and exercise training on cerebrovascular hemodynamic variables post-stroke. PURPOSE This systematic review and meta-analysis 1) examined the effects of acute exercise and exercise training on cerebrovascular hemodynamic variables reported in the stroke exercise literature; and 2) synthesized the peak middle cerebral artery blood velocity (MCAv) achieved during an acute bout of moderate-intensity exercise in individuals post-stroke. METHODS Six databases (MEDLINE, EMBASE, Web of Science, CINAHL, PsycINFO, AMED) were searched from inception to December 1st 2021, for studies that examined the effect of acute exercise or exercise training on cerebrovascular hemodynamics in adults post-stroke. Two reviewers conducted title and abstract screening, full-text evaluation, data extraction, and quality appraisal. Random effects models were used in meta-analysis. RESULTS Nine studies, including 4 acute exercise (n=61) and 5 exercise training studies (n=193), were included. Meta-analyses were not statistically feasible for several cerebrovascular hemodynamic variables. Descriptive analysis reveals that exercise training may increase cerebral blood flow and cerebrovascular reactivity to carbon dioxide among individuals post-stroke. Meta-analysis of three acute exercise studies revealed no significant changes in MCAv during acute moderate intensity exercise (n=48 participants, mean difference = 5.2 cm/s, 95% CI [-0.6, 11.0], P=0.08) compared to resting MCAv values. CONCLUSION This review suggests that individuals post-stroke may have attenuated cerebrovascular hemodynamics as measured by the MCAv during acute moderate-intensity exercise. Higher quality research utilizing agreed upon hemodynamic variables are needed to synthesize the effects of exercise training on cerebrovascular hemodynamics post-stroke.
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Affiliation(s)
- Kevin Moncion
- School of Rehabilitation Sciences, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Elric Y Allison
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, Ontario, Canada
| | - Baraa K Al-Khazraji
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, Ontario, Canada
| | - Maureen J MacDonald
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, Ontario, Canada
| | - Marc Roig
- School of Physical and Occupational Therapy, Faculty of Medicine, McGill University, Montreal, Québec, Canada
| | - Ada Tang
- School of Rehabilitation Sciences, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
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10
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Moriyama S, Ichinose M, Dobashi K, Matsutake R, Sakamoto M, Fujii N, Nishiyasu T. Hypercapnia elicits differential vascular and blood flow responses in the cerebral circulation and active skeletal muscles in exercising humans. Physiol Rep 2022; 10:e15274. [PMID: 35466573 PMCID: PMC9035754 DOI: 10.14814/phy2.15274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 03/29/2022] [Indexed: 12/02/2022] Open
Abstract
The purpose of this study was to investigate the effects of a rise in arterial carbon dioxide pressure (PaCO2) on vascular and blood flow responses in the cerebral circulation and active skeletal muscles during dynamic exercise in humans. Thirteen healthy young adults (three women) participated in hypercapnia and normocapnia trials. In both trials, participants performed a two‐legged dynamic knee extension exercise at a constant workload that increased heart rate to roughly 100 beats min−1. In the hypercapnia trial, participants performed the exercise with spontaneous breathing while end‐tidal carbon dioxide pressure (PETCO2), an index of PaCO2, was held at 60 mmHg by inhaling hypercapnic gas (O2: 20.3 ± 0.1%; CO2: 6.0 ± 0.5%). In the normocapnia trial, minute ventilation during exercise was matched to the value in the hypercapnia trial by performing voluntary hyperventilation with PETCO2 clamped at baseline level (i.e., 40–45 mmHg) through inhalation of mildly hypercapnic gas (O2: 20.6 ± 0.1%; CO2: 2.7 ± 1.0%). Middle cerebral artery mean blood velocity and the cerebral vascular conductance index were higher in the hypercapnia trial than in the normocapnia trial. By contrast, vascular conductance in the exercising leg was lower in the hypercapnia trial than in the normocapnia trial. Blood flow to the exercising leg did not differ between the two trials. These results demonstrate that hypercapnia‐induced vasomotion in active skeletal muscles is opposite to that in the cerebral circulation. These differential vascular responses may cause a preferential rise in cerebral blood flow.
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Affiliation(s)
- Shodai Moriyama
- Faculty of Health and Sport Sciences University of Tsukuba Tsukuba City Ibaraki Japan
| | - Masashi Ichinose
- Human Integrative Physiology Laboratory School of Business Administration Meiji University Tokyo Japan
| | - Kohei Dobashi
- Faculty of Health and Sport Sciences University of Tsukuba Tsukuba City Ibaraki Japan
- Faculty of Education Hokkaido University of Education Hokkaido Japan
| | - Ryoko Matsutake
- Faculty of Health and Sport Sciences University of Tsukuba Tsukuba City Ibaraki Japan
| | - Mizuki Sakamoto
- Faculty of Health and Sport Sciences University of Tsukuba Tsukuba City Ibaraki Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences University of Tsukuba Tsukuba City Ibaraki Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences University of Tsukuba Tsukuba City Ibaraki Japan
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11
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Washio T, Watanabe H, Suzuki K, Saito S, Ogoh S. Site-specific different dynamic cerebral autoregulation and cerebrovascular response to carbon dioxide in posterior cerebral circulation during isometric exercise in healthy young men. Auton Neurosci 2022; 238:102943. [PMID: 35086019 DOI: 10.1016/j.autneu.2022.102943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/16/2021] [Accepted: 01/16/2022] [Indexed: 11/23/2022]
Abstract
Different cerebral blood flow (CBF) responses to exercise between the posterior cerebral artery (PCA) and vertebral artery (VA) have been previously observed, though the physiological mechanisms remain unknown. There is regional heterogeneity in sympathetic innervation between the PCA and VA, which may affect CBF regulation, especially during sympathoexcitation. Thus, in the present study, we hypothesized that different CBF regulatory mechanisms between PCA and VA contribute to heterogeneous CBF responses to isometric exercise. To test this hypothesis, in thirteen healthy young men, dynamic cerebral autoregulation (CA) and cerebrovascular CO2 reactivity (CVR), were identified in each artery during a 2-min isometric handgrip (IHG) exercise at 30% of maximum voluntary contraction. Similar to previous data, PCA cerebrovascular conductance (CVC) index was decreased from rest (P < 0.004), but not VA CVC during IHG exercise (P > 0.084). Dynamic CA in both PCA and VA were unaltered during the IHG exercise (P = 0.129). On the other hand, PCA CVR was increased during the IHG exercise (P < 0.001) while VA CVR was unchanged (P = 0.294). In addition, individual exercise-induced changes in end-tidal partial pressure of CO2 was related to the individual change in PCA blood velocity (P < 0.046), but was not observed for VA blood flow (P > 0.420). Therefore, these exercise-induced differences in CVR between PCA and VA may contribute to exercise-induced heterogeneous CBF response in the posterior cerebral circulation. These findings indicate that the site-specific posterior CBF should be considered in further research for assessing posterior cerebral circulation.
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Affiliation(s)
- Takuro Washio
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Hironori Watanabe
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Kazuya Suzuki
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Shotaro Saito
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan; Neurovascular Research Laboratory, University of South Wales, UK.
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12
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Lake SL, Guadagni V, Kendall KD, Chadder M, Anderson TJ, Leigh R, Rawling JM, Hogan DB, Hill MD, Poulin MJ. Aerobic exercise training in older men and women-Cerebrovascular responses to submaximal exercise: Results from the Brain in Motion study. Physiol Rep 2022; 10:e15158. [PMID: 35212167 PMCID: PMC8874289 DOI: 10.14814/phy2.15158] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 12/07/2021] [Indexed: 12/12/2022] Open
Abstract
Physical inactivity is a leading modifiable risk factor for cardiovascular and cerebrovascular disease, cognitive dysfunction, and global mortality. Regular exercise might mitigate age-related declines in cardiovascular and cerebrovascular function. In this study, we hypothesize that a 6-month aerobic exercise intervention will lead to a decrease in cerebrovascular resistance index (CVRi) and to an increase in cerebral blood flow (CBF) and cerebrovascular conductance index (CVCi) during two submaximal exercise workloads (40% VO2 max and 65 W), intensities that have been shown to be comparable to activities of daily life. Two hundred three low-active healthy men and women enrolled in the Brain in Motion study, completed a 6-month exercise intervention and underwent submaximal and maximal tests pre-/post-intervention. The intervention improved the gas exchange threshold and maximal oxygen consumption (VO2 max), with no change in heart rate at VO2 max, during the treadmill VO2 max test. Heart rate and CVRi decreased from pre-intervention values during both relative (40% VO2 max) and absolute (65 W) submaximal exercise tests. Blood flow velocity in the middle cerebral artery and CVCi increased post-intervention during 40% VO2 max and 65 W. Changes in mean arterial pressure were found only during the absolute component (65 W). Our study demonstrates that aerobic exercise improves not only cardiorespiratory indices but also cerebrovascular function at submaximal workloads which may help to mitigate age-related declines in everyday life. Investigation of the mechanisms underlying the decline in cardiovascular and cerebrovascular capacity with aging has important implications for the maintenance of health and continued independence of older adults.
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Affiliation(s)
- Sonja L Lake
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Clinical & Translational Exercise Physiology Lab, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Veronica Guadagni
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,O'Brien Institute for Public Health, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Karen D Kendall
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Clinical & Translational Exercise Physiology Lab, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Michaela Chadder
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Clinical & Translational Exercise Physiology Lab, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Todd J Anderson
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Richard Leigh
- Department of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jean M Rawling
- Department of Family Medicine, University of Calgary, Calgary, Alberta, Canada
| | - David B Hogan
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,O'Brien Institute for Public Health, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Division of Geriatric Medicine, Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Michael D Hill
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Marc J Poulin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,O'Brien Institute for Public Health, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Brenda Strafford Foundation Chair in Alzheimer Research, Calgary, Alberta, Canada
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13
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Schultz Martins R, Wallace PJ, Steele SW, Scott JS, Taber MJ, Hartley GL, Cheung SS. The Clamping of End-Tidal Carbon Dioxide Does Not Influence Cognitive Function Performance During Moderate Hyperthermia With or Without Skin Temperature Manipulation. Front Psychol 2021; 12:788027. [PMID: 35002880 PMCID: PMC8730541 DOI: 10.3389/fpsyg.2021.788027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 11/26/2021] [Indexed: 11/13/2022] Open
Abstract
Increases in body temperature from heat stress (i.e., hyperthermia) generally impairs cognitive function across a range of domains and complexities, but the relative contribution from skin versus core temperature changes remains unclear. Hyperthermia also elicits a hyperventilatory response that decreases the partial pressure of end-tidal carbon dioxide (PetCO2) and subsequently cerebral blood flow that may influence cognitive function. We studied the role of skin and core temperature along with PetCO2 on cognitive function across a range of domains. Eleven males completed a randomized, single-blinded protocol consisting of poikilocapnia (POIKI, no PetCO2 control) or isocapnia (ISO, PetCO2 maintained at baseline levels) during passive heating using a water-perfused suit (water temperature ~ 49°C) while middle cerebral artery velocity (MCAv) was measured continuously as an index of cerebral blood flow. Cognitive testing was completed at baseline, neutral core-hot skin (37.0 ± 0.2°C-37.4 ± 0.3°C), hot core-hot skin (38.6 ± 0.3°C-38.7 ± 0.2°C), and hot core-cooled skin (38.5 ± 0.3°C-34.7 ± 0.6°C). The cognitive test battery consisted of a detection task (psychomotor processing), 2-back task (working memory), set-shifting and Groton Maze Learning Task (executive function). At hot core-hot skin, poikilocapnia led to significant (both p < 0.05) decreases in PetCO2 (∆−21%) and MCAv (∆−26%) from baseline, while isocapnia clamped PetCO2 (∆ + 4% from baseline) leading to a significantly (p = 0.023) higher MCAv (∆−18% from baseline) compared to poikilocapnia. There were no significant differences in errors made on any task (all p > 0.05) irrespective of skin temperature or PetCO2 manipulation. We conclude that neither skin temperature nor PetCO2 maintenance significantly alter cognitive function during passive hyperthermia.
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Affiliation(s)
- Ricardo Schultz Martins
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Phillip J. Wallace
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Scott W. Steele
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Jake S. Scott
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Michael J. Taber
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- NM Consulting Inc., St. Catharines, ON, Canada
| | - Geoffrey L. Hartley
- Department of Physical and Health Education, Nipissing University, North Bay, ON, Canada
| | - Stephen S. Cheung
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- *Correspondence: Stephen S. Cheung,
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14
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Koep JL, Weston ME, Barker AR, Bailey TG, Coombes JS, Lester A, Bond B. The within- and between-day reliability of cerebrovascular reactivity using traditional and novel analytical approaches. Exp Physiol 2021; 107:29-41. [PMID: 34806238 DOI: 10.1113/ep090031] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 11/15/2021] [Indexed: 12/14/2022]
Abstract
NEW FINDINGS What is the central question of the study? What is the reliability of middle cerebral artery velocity cerebrovascular reactivity (CVR) when using traditional and novel outcomes, as measured by transcranial Doppler? What is the main finding and its importance? Traditional CVR approaches presented acceptable reproducibility but should be expressed as an absolute CVR. Large within- and between-individual differences in the middle cerebral artery velocity response profile support using a dynamic peak, rather than a set time point, for the most reliable interpretation. The study highlights the utility of novel kinetic CVR outcomes, but due to increased variability in time-based metrics, this analysis requires larger sample sizes than traditional methods. ABSTRACT Cerebrovascular reactivity (CVR) of middle cerebral artery velocity (MCAv) to CO2 is a common method to assess cerebrovascular function. Yet, the approaches used to calculate CVR outcomes vary. The aim of this study was to explore the within- and between-day reliability of traditional CVR outcomes. The second aim was to explore the reliability of novel kinetic-based analyses. Healthy adults (n = 10, 22.3 ± 3.4 years) completed assessments of CVR over 4 min using a fixed fraction of inspired CO2 (6%). This was repeated across four separate visits (between-day), and on one visit measures were repeated 2.5 h later (within-day). No mean biases were present between assessments for traditional CVR metrics, expressed as absolute (cm/s/mmHg) or relative (%/mmHg) outcomes (minute 3, minute 4, peak 1 s, peak 30 s) (between-day: P > 0.14, ηp 2 < 0.20; within-day: P > 0.22, d > 0.27). Absolute, rather than relative, CVR yielded the most reproducible parameters (coefficient of variation: 8.1-13.2% vs. 14-83%, respectively). There were significant differences between CVR outcomes (P < 0.001, ηp 2 > 0.89) dependent on the time point used to determine CVR, as a steady state MCAv response was rarely observed. Furthermore, the MCAv response was not reproducible within an individual (κ = 0.15, P = 0.09). No mean differences were present for novel kinetic outcomes (amplitude, time-delay, time constant) (between-day: P > 0.05, d < 0.33; within-day: P > 0.38, d < 0.25). The results support the need for standardisation and indicate CVR should be defined as a dynamic peak, rather than a set time point for increased reliability. For novel kinetic outcomes variability was greater (CV: 8.7-120.9%) due to the nature of time-based metrics.
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Affiliation(s)
- Jodie L Koep
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.,Physiology and Ultrasound Laboratory in Science and Exercise, School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Max E Weston
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.,Physiology and Ultrasound Laboratory in Science and Exercise, School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Alan R Barker
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Tom G Bailey
- Physiology and Ultrasound Laboratory in Science and Exercise, School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Queensland, Australia.,School of Nursing Midwifery and Social Work, University of Queensland, Brisbane, Queensland, Australia
| | - Jeff S Coombes
- Physiology and Ultrasound Laboratory in Science and Exercise, School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Alice Lester
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Bert Bond
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
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15
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Caldwell HG, Carr JMJR, Minhas JS, Swenson ER, Ainslie PN. Acid-base balance and cerebrovascular regulation. J Physiol 2021; 599:5337-5359. [PMID: 34705265 DOI: 10.1113/jp281517] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 10/19/2021] [Indexed: 12/22/2022] Open
Abstract
The regulation and defence of intracellular pH is essential for homeostasis. Indeed, alterations in cerebrovascular acid-base balance directly affect cerebral blood flow (CBF) which has implications for human health and disease. For example, changes in CBF regulation during acid-base disturbances are evident in conditions such as chronic obstructive pulmonary disease and diabetic ketoacidosis. The classic experimental studies from the past 75+ years are utilized to describe the integrative relationships between CBF, carbon dioxide tension (PCO2 ), bicarbonate (HCO3 - ) and pH. These factors interact to influence (1) the time course of acid-base compensatory changes and the respective cerebrovascular responses (due to rapid exchange kinetics between arterial blood, extracellular fluid and intracellular brain tissue). We propose that alterations in arterial [HCO3 - ] during acute respiratory acidosis/alkalosis contribute to cerebrovascular acid-base regulation; and (2) the regulation of CBF by direct changes in arterial vs. extravascular/interstitial PCO2 and pH - the latter recognized as the proximal compartment which alters vascular smooth muscle cell regulation of CBF. Taken together, these results substantiate two key ideas: first, that the regulation of CBF is affected by the severity of metabolic/respiratory disturbances, including the extent of partial/full acid-base compensation; and second, that the regulation of CBF is independent of arterial pH and that diffusion of CO2 across the blood-brain barrier is integral to altering perivascular extracellular pH. Overall, by realizing the integrative relationships between CBF, PCO2 , HCO3 - and pH, experimental studies may provide insights to improve CBF regulation in clinical practice with treatment of systemic acid-base disorders.
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Affiliation(s)
- Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan, Kelowna, Canada
| | - Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan, Kelowna, Canada
| | - Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Erik R Swenson
- Pulmonary, Critical Care and Sleep Medicine Division, University of Washington, and VA Puget Sound Healthcare System, Seattle, WA, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan, Kelowna, Canada
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16
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Sobczyk O, Fierstra J, Venkatraghavan L, Poublanc J, Duffin J, Fisher JA, Mikulis DJ. Measuring Cerebrovascular Reactivity: Sixteen Avoidable Pitfalls. Front Physiol 2021; 12:665049. [PMID: 34305634 PMCID: PMC8294324 DOI: 10.3389/fphys.2021.665049] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 06/07/2021] [Indexed: 12/04/2022] Open
Abstract
An increase in arterial PCO2 is the most common stressor used to increase cerebral blood flow for assessing cerebral vascular reactivity (CVR). That CO2 is readily obtained, inexpensive, easy to administer, and safe to inhale belies the difficulties in extracting scientifically and clinically relevant information from the resulting flow responses. Over the past two decades, we have studied more than 2,000 individuals, most with cervical and cerebral vascular pathology using CO2 as the vasoactive agent and blood oxygen-level-dependent magnetic resonance imaging signal as the flow surrogate. The ability to deliver different forms of precise hypercapnic stimuli enabled systematic exploration of the blood flow-related signal changes. We learned the effect on CVR of particular aspects of the stimulus such as the arterial partial pressure of oxygen, the baseline PCO2, and the magnitude, rate, and pattern of its change. Similarly, we learned to interpret aspects of the flow response such as its magnitude, and the speed and direction of change. Finally, we were able to test whether the response falls into a normal range. Here, we present a review of our accumulated insight as 16 “lessons learned.” We hope many of these insights are sufficiently general to apply to a range of types of CO2-based vasoactive stimuli and perfusion metrics used for CVR.
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Affiliation(s)
- Olivia Sobczyk
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada.,Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - Jorn Fierstra
- Department of Neurosurgery, University Hospital Zurich, Zürich, Switzerland
| | - Lakshmikumar Venkatraghavan
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - James Duffin
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Joseph A Fisher
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
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17
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Moir ME, Vermeulen TD, Smith SO, Woehrle E, Matushewski BJ, Zamir M, Shoemaker JK. Vasodilatation by carbon dioxide and sodium nitroglycerin reduces compliance of the cerebral arteries in humans. Exp Physiol 2021; 106:1679-1688. [PMID: 34117663 DOI: 10.1113/ep089533] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 06/09/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Vascular compliance importantly contributes to the regulation of cerebral perfusion and complex mechanisms are known to influence compliance of a vascular bed: while vasodilatation mediates changes in vascular resistance, does it also affect compliance, particularly in the cerebral vasculature? What is the main finding and its importance? Cerebral vasodilatation, elicited by hypercapnia and sodium nitroglycerin administration, reduced cerebrovascular compliance by approximately 26% from baseline. This study provides new insight into mechanisms mediating cerebrovascular compliance. ABSTRACT Changes in vascular resistance and vascular compliance contribute to the regulation of cerebral perfusion. While changes in vascular resistance are known to be mediated by vasodilatation, the mechanisms contributing to changes in vascular compliance are complex. In particular, whether vasodilatation affects compliance of the vasculature within the cranium remains unknown. Therefore, the present study examined the impact of two vasodilatation pathways on cerebrovascular compliance in humans. Fifteen young, healthy adults (26 ± 5 years, seven females) completed two protocols: (i) sublingual sodium nitroglycerin (SNG; 0.4 mg) and (ii) hypercapnia (5-6% carbon dioxide gas mixture for 4 min). Blood pressure waveforms (finger photoplethysmography) and middle cerebral artery blood velocity waveforms (transcranial Doppler ultrasound) were input into a modified Windkessel model and an index of cerebrovascular compliance (Ci) was calculated. During the SNG protocol, Ci decreased 24 ± 17% from baseline ((5.0 ± 2.3) × 10-4 cm s-1 mmHg-1 ) to minute 10 ((3.6 ± 1.2) × 10-4 cm s-1 mmHg-1 ; P = 0.009). During the hypercapnia protocol, Ci decreased 28 ± 9% from baseline ((4.4 ± 1.9) × 10-4 cm s-1 mmHg-1 ) to minute 4 ((3.1 ± 1.4) × 10-4 cm s-1 mmHg-1 ; P < 0.001). Cerebral vasodilatory stimuli induced by nitric oxide and carbon dioxide mechanisms reduced compliance of the cerebral vascular bed by approximately 26% from supine baseline values.
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Affiliation(s)
- M Erin Moir
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | - Tyler D Vermeulen
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | - Sydney O Smith
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | - Emilie Woehrle
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | - Brad J Matushewski
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | - Mair Zamir
- Department of Applied Mathematics, University of Western Ontario, London, Ontario, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - J Kevin Shoemaker
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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18
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Caldwell HG, Howe CA, Hoiland RL, Carr JMJR, Chalifoux CJ, Brown CV, Patrician A, Tremblay JC, Panerai RB, Robinson TG, Minhas JS, Ainslie PN. Alterations in arterial CO 2 rather than pH affect the kinetics of neurovascular coupling in humans. J Physiol 2021; 599:3663-3676. [PMID: 34107079 DOI: 10.1113/jp281615] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/08/2021] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS We investigated the influence of arterial P C O 2 ( P aC O 2 ) with and without acute experimental metabolic alkalosis on neurovascular coupling (NVC). We assessed stepwise iso-oxic alterations in P aC O 2 prior to and following intravenous NaHCO3 to acutely elevate arterial pH and [HCO3 - ]. The NVC response was not altered following NaHCO3 between stepwise P aC O 2 stages; therefore, NVC is acutely mediated by P aC O 2 rather than the prevailing arterial [H+ ]/pH. The NVC response was attenuated by 27-38% with -10 mmHg P aC O 2 and the absolute peak change was reduced by -19% with +10 mmHg P aC O 2 irrespective of acutely elevated arterial pH/[HCO3 - ]. The NVC kinetics (i.e. time to peak) were markedly slower with hypercapnia versus hypocapnia (24 ± 5 vs. 7 ± 5 s, respectively) likely indicating an influence of resting cerebrovascular tone on NVC responsiveness. ABSTRACT Elevations in cerebral metabolism necessitate appropriate coordinated and localized increases in cerebral blood flow (i.e. neurovascular coupling; NVC). Recent pre-clinical work indicates that arterial P C O 2 ( P aC O 2 ) mediates NVC independently of arterial/extracellular pH; this has yet to be experimentally tested in humans. The goal of this study was to investigate the hypotheses that: (1) the NVC response would be unaffected by acute experimentally elevated arterial pH; rather, P aC O 2 would regulate any changes in NVC; and (2) stepwise respiratory alkalosis and acidosis would each progressively reduce the NVC response. Ten healthy males completed a standardized visual stimulus-evoked NVC test during matched stepwise iso-oxic alterations in P aC O 2 (hypocapnia: -5, -10 mmHg; hypercapnia: +5, +10 mmHg) prior to and following intravenous NaHCO3 (8.4%, 50 mEq/50 ml) that elevated arterial pH (7.406 ± 0.019 vs. 7.457 ± 0.029; P < 0.001) and [HCO3 - ] (26.2 ± 1.5 vs. 29.3 ± 0.9 mEq/l; P < 0.001). Although the NVC response was collectively attenuated by 27-38% with -10 mmHg P aC O 2 (stage post hoc: all P < 0.05), this response was unaltered following NaHCO3 (all P > 0.05) irrespective of the higher pH (P = 0.002) at each matched stage of P aC O 2 (P = 0.417). The absolute peak change was reduced by -19 ± 41% with +10 mmHg P aC O 2 irrespective of acutely elevated arterial pH/[HCO3 - ] (stage post hoc: P = 0.022). The NVC kinetics (i.e. time to peak) were markedly slower with hypercapnia versus hypocapnia (24 ± 5 vs. 7 ± 5 s, respectively; stage effect: P < 0.001). Overall, these findings indicate that temporal patterns in NVC are acutely regulated by P aC O 2 rather than arterial pH per se in the setting of acute metabolic alkalosis in humans.
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Affiliation(s)
- Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, V1V 1V7, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, V1V 1V7, Canada
| | - Ryan L Hoiland
- Department of Anesthesiology, Pharmacology, and Therapeutics, Vancouver General Hospital, West 12th Avenue, University of British Columbia, Vancouver, BC, V5Z 1M9, Canada.,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, V1V 1V7, Canada
| | - Carter J Chalifoux
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, V1V 1V7, Canada
| | - Courtney V Brown
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, V1V 1V7, Canada
| | - Alexander Patrician
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, V1V 1V7, Canada
| | - Joshua C Tremblay
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, V1V 1V7, Canada
| | - Ronney B Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Thompson G Robinson
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, V1V 1V7, Canada
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19
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Al-Khazraji BK, Buch S, Kadem M, Matushewski BJ, Norozi K, Menon RS, Shoemaker JK. Protocol-dependence of middle cerebral artery dilation to modest hypercapnia. Appl Physiol Nutr Metab 2021; 46:1038-1046. [PMID: 34139129 DOI: 10.1139/apnm-2021-0220] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is a need for improved understanding of how different cerebrovascular reactivity (CVR) protocols affect vascular cross-sectional area (CSA) to reduce error in CVR calculations when measures of vascular CSA are not feasible. In human participants, we delivered ∼±4 mm Hg end-tidal partial pressure of CO2 (PETCO2) relative to baseline through controlled delivery, and measured changes in middle cerebral artery (MCA) CSA (7 Tesla magnetic resonance imaging (MRI)), blood velocity (transcranial Doppler and Phase contrast MRI), and calculated CVR based on a 3-minute steady-state (+4 mm Hg PETCO2) and a ramp (-3 to +4 mm Hg of PETCO2). We observed that (1) the MCA did not dilate during the ramp protocol (slope for CSA across time P > 0.05; R2 = 0.006), but did dilate by ∼7% during steady-state hypercapnia (P < 0.05); and (2) MCA blood velocity CVR was not different between ramp and steady-state hypercapnia protocols (ramp: 3.8 ± 1.7 vs. steady-state: 4.0 ± 1.6 cm/s/mm Hg), although calculated MCA blood flow CVR was ∼40% greater during steady-state hypercapnia than during ramp (P < 0.05) with the discrepancy due to MCA CSA changes during steady-state hypercapnia. We propose that a ramp model, across a delta of -3 to +4 mm Hg PETCO2, may provide an alternative approach to collecting CVR measures in young adults with transcranial Doppler when CSA measures are not feasible. Novelty: We optimized a magnetic resonance imaging sequence to measure dynamic middle cerebral artery (MCA) cross-sectional area (CSA). A ramp model of hypercapnia elicited similar MCA blood velocity reactivity as the steady-state model while maintaining MCA CSA.
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Affiliation(s)
- Baraa K Al-Khazraji
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, ON, Canada
| | - Sagar Buch
- Centre for Functional and Metabolic Mapping, Robarts Research Institute, London, ON, Canada
| | - Mason Kadem
- School of Biomedical Engineering, McMaster University, Hamilton, ON, Canada
| | - Brad J Matushewski
- School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada
| | - Kambiz Norozi
- Department of Pediatrics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Department of Pediatric Cardiology, Hannover Medical School, Hannover, Germany
| | - Ravi S Menon
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Centre for Functional and Metabolic Mapping, Robarts Research Institute
| | - J Kevin Shoemaker
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,School of Kinesiology, Faculty of Health Sciences
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20
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Carr JMJR, Caldwell HG, Ainslie PN. Cerebral blood flow, cerebrovascular reactivity and their influence on ventilatory sensitivity. Exp Physiol 2021; 106:1425-1448. [PMID: 33932955 DOI: 10.1113/ep089446] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 04/26/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the topic of this review? Cerebrovascular reactivity to CO2 , which is a principal factor in determining ventilatory responses to CO2 through the role reactivity plays in determining cerebral extra- and intracellular pH. What advances does it highlight? Recent animal evidence suggests central chemoreceptor vasculature may demonstrate regionally heterogeneous cerebrovascular reactivity to CO2 , potentially as a protective mechanism against excessive CO2 washout from the central chemoreceptors, thereby allowing ventilation to reflect the systemic acid-base balance needs (respiratory changes in P aC O 2 ) rather than solely the cerebral needs. Ventilation per se does not influence cerebrovascular reactivity independent of changes in P aC O 2 . ABSTRACT Alveolar ventilation and cerebral blood flow are both predominantly regulated by arterial blood gases, especially arterial P C O 2 , and so are intricately entwined. In this review, the fundamental mechanisms underlying cerebrovascular reactivity and central chemoreceptor control of breathing are covered. We discuss the interaction of cerebral blood flow and its reactivity with the control of ventilation and ventilatory responsiveness to changes in P C O 2 , as well as the lack of influence of ventilation itself on cerebrovascular reactivity. We briefly summarize the effects of arterial hypoxaemia on the relationship between ventilatory and cerebrovascular response to both P C O 2 and P O 2 . We then highlight key methodological considerations regarding the interaction of reactivity and ventilatory sensitivity, including the following: regional heterogeneity of cerebrovascular reactivity; a pharmacological approach for the reduction of cerebral blood flow; reactivity assessment techniques; the influence of mean arterial blood pressure; and sex-related differences. Finally, we discuss ventilatory and cerebrovascular control in the context of high altitude and congestive heart failure. Future research directions and pertinent questions of interest are highlighted throughout.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
| | - Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
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21
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Labrecque L, Drapeau A, Rahimaly K, Imhoff S, Brassard P. Dynamic cerebral autoregulation and cerebrovascular carbon dioxide reactivity in middle and posterior cerebral arteries in young endurance-trained women. J Appl Physiol (1985) 2021; 130:1724-1735. [PMID: 33955257 DOI: 10.1152/japplphysiol.00963.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The integrated responses regulating cerebral blood flow are understudied in women, particularly in relation to potential regional differences. In this study, we compared dynamic cerebral autoregulation (dCA) and cerebrovascular reactivity to carbon dioxide (CVRco2) in the middle (MCA) and posterior cerebral arteries (PCA) in 11 young endurance-trained women (age, 25 ± 4 yr; maximal oxygen uptake, 48.1 ± 4.1 mL·kg-1·min-1). dCA was characterized using a multimodal approach including a sit-to-stand and a transfer function analysis (TFA) of forced blood pressure oscillations (repeated squat-stands executed at 0.05 Hz and 0.10 Hz). The hyperoxic rebreathing test was utilized to characterize CVRco2. Upon standing, the percent reduction in blood velocity per percent reduction in mean arterial pressure during initial orthostatic stress (0-15 s after sit-to-stand), the onset of the regulatory response, and the rate of regulation did not differ between MCA and PCA (all P > 0.05). There was an ANOVA effect of anatomical location for TFA gain (P < 0.001) and a frequency effect for TFA phase (P < 0.001). However, normalized gain was not different between arteries (P = 0.18). Absolute CVRco2 was not different between MCA and PCA (1.55 ± 0.81 vs. 1.30 ± 0.49 cm·s-1/Torr, P = 0.26). Relative CVRco2 was 39% lower in the MCA (2.16 ± 1.02 vs. 3.00 ± 1.09%/Torr, P < 0.01). These findings indicate that the cerebral pressure-flow relationship appears to be similar between the MCA and the PCA in young endurance-trained women. The absence of regional differences in absolute CVRco2 could be women specific, although a direct comparison with a group of men will be necessary to address that issue.NEW & NOTEWORTHY Herein, we describe responses from two major mechanisms regulating cerebral blood flow with a special attention on regional differences in young endurance-trained women. The novel findings are that dynamic cerebral autoregulation and absolute cerebrovascular reactivity to carbon dioxide appear similar between the middle and posterior cerebral arteries of these young women.
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Affiliation(s)
- Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec City, Québec, Canada
| | - Audrey Drapeau
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec City, Québec, Canada
| | - Kevan Rahimaly
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec City, Québec, Canada
| | - Sarah Imhoff
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec City, Québec, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec City, Québec, Canada
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22
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Rosenberg AJ, Kay VL, Anderson GK, Luu ML, Barnes HJ, Sprick JD, Rickards CA. The impact of acute central hypovolemia on cerebral hemodynamics: does sex matter? J Appl Physiol (1985) 2021; 130:1786-1797. [PMID: 33914663 DOI: 10.1152/japplphysiol.00499.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Trauma-induced hemorrhage is a leading cause of disability and death due, in part, to impaired perfusion and oxygenation of the brain. It is unknown if cerebrovascular responses to blood loss are differentiated based on sex. We hypothesized that compared to males, females would have reduced tolerance to simulated hemorrhage induced by maximal lower body negative pressure (LBNP), and this would be associated with an earlier reduction in cerebral blood flow and cerebral oxygenation. Healthy young males (n = 29, 26 ± 4 yr) and females (n = 23, 27 ± 5 yr) completed a step-wise LBNP protocol to presyncope. Mean arterial pressure (MAP), stroke volume (SV), middle cerebral artery velocity (MCAv), end-tidal CO2 (etCO2), and cerebral oxygen saturation (ScO2) were measured continuously. Unexpectedly, tolerance to LBNP was similar between the sexes (males, 1,604 ± 68 s vs. females, 1,453 ± 78 s; P = 0.15). Accordingly, decreases (%Δ) in MAP, SV, MCAv, and ScO2 were similar between males and females throughout LBNP and at presyncope (P ≥ 0.20). Interestingly, although decreases in etCO2 were similar between the sexes throughout LBNP (P = 0.16), at presyncope, the %Δ etCO2 from baseline was greater in males compared to females (-30.8 ± 2.6% vs. -21.3 ± 3.0%; P = 0.02). Contrary to our hypothesis, sex does not influence tolerance, or the central or cerebral hemodynamic responses to simulated hemorrhage. However, the etCO2 responses at presyncope do suggest potential sex differences in cerebral vascular sensitivity to CO2 during central hypovolemia.NEW & NOTEWORTHY Tolerance and cerebral blood velocity responses to simulated hemorrhage (elicited by lower body negative pressure) were similar between male and female subjects. Interestingly, the change in etCO2 from baseline was greater in males compared to females at presyncope, suggesting potential sex differences in cerebral vascular sensitivity to CO2 during simulated hemorrhage. These findings may facilitate development of individualized therapeutic interventions to improve survival from hemorrhagic injuries in both men and women.
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Affiliation(s)
- Alexander J Rosenberg
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas.,Integrative Physiology Laboratory, Department of Kinesiology and Nutrition, University of Illinois at Chicago, Illinois
| | - Victoria L Kay
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Garen K Anderson
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - My-Loan Luu
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Haley J Barnes
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Justin D Sprick
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas.,Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Caroline A Rickards
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
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23
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Fisher JA, Mikulis DJ. Cerebrovascular Reactivity: Purpose, Optimizing Methods, and Limitations to Interpretation - A Personal 20-Year Odyssey of (Re)searching. Front Physiol 2021; 12:629651. [PMID: 33868001 PMCID: PMC8047146 DOI: 10.3389/fphys.2021.629651] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 03/10/2021] [Indexed: 11/18/2022] Open
Abstract
The brain is a neurovascular organ. A stimulus-response approach is effective in interrogating the physiology of its vasculature. Ideally, the stimulus is standardized across patients, and in a single patient over time. We developed a standard stimulus and attempted to measure, classify, and interpret the many forms of responses. Over the past 20 years, our work has delivered nuanced insights into normal cerebral vascular physiology, as well as adaptive physiological responses in the presence of disease. The trajectory of our understanding did not follow a logical linear progression; rather, it emerged as a coalescence of new, old, and previously dismissed, ideas that had accumulated over time. In this essay, we review what we believe were our most valuable - and sometimes controversial insights during our two decades-long journey.
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Affiliation(s)
- Joseph A. Fisher
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - David J. Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
- The Joint Department of Medical Imaging, Toronto Western Hospital, University of Toronto, Toronto, ON, Canada
- Techna Institute & Koerner Scientist in MR Imaging, University Health Network, Toronto, ON, Canada
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24
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Rosenberg AJ, Kay VL, Anderson GK, Sprick JD, Rickards CA. A comparison of protocols for simulating hemorrhage in humans: step versus ramp lower body negative pressure. J Appl Physiol (1985) 2021; 130:380-389. [PMID: 33211600 DOI: 10.1152/japplphysiol.00230.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lower body negative pressure (LBNP) elicits central hypovolemia, and it has been used to simulate the cardiovascular and cerebrovascular responses to hemorrhage in humans. LBNP protocols commonly use progressive stepwise reductions in chamber pressure for specific time periods. However, continuous ramp LBNP protocols have also been utilized to simulate the continuous nature of most bleeding injuries. The aim of this study was to compare tolerance and hemodynamic responses between these two LBNP profiles. Healthy human subjects (N = 19; age, 27 ± 4 y; 7 female/12 male) completed a 1) step LBNP protocol (5-min steps) and 2) continuous ramp LBNP protocol (3 mmHg/min), both to presyncope. Heart rate (HR), mean arterial pressure (MAP), stroke volume (SV), middle and posterior cerebral artery velocity (MCAv and PCAv), cerebral oxygen saturation (ScO2), and end-tidal CO2 (etCO2) were measured. LBNP tolerance, via the cumulative stress index (CSI, summation of chamber pressure × time at each pressure), and hemodynamic responses were compared between the two protocols. The CSI (step: 911 ± 97 mmHg/min vs. ramp: 823 ± 83 mmHg/min; P = 0.12) and the magnitude of central hypovolemia (%Δ SV, step: -54.6% ± 2.6% vs. ramp: -52.1% ± 2.8%; P = 0.32) were similar between protocols. Although there were no differences between protocols for the maximal %Δ HR (P = 0.88), the %Δ MAP during the step protocol was attenuated (P = 0.05), and the reductions in MCAv, PCAv, ScO2, and etCO2 were greater (P ≤ 0.08) when compared with the ramp protocol at presyncope. These results indicate that when comparing cardiovascular responses to LBNP across different laboratories, the specific pressure profile must be considered as a potential confounding factor.NEW & NOTEWORTHY Ramp lower body negative pressure (LBNP) protocols have been utilized to simulate the continuous nature of bleeding injuries. However, it unknown if tolerance or the physiological responses to ramp LBNP are similar to the more common stepwise LBNP protocol. We report similar tolerance between the two protocols, but the step protocol elicited a greater increase in cerebral oxygen extraction in the presence of reduced blood flow, presumably facilitating the matching of metabolic supply and demand.
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Affiliation(s)
- Alexander J Rosenberg
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Victoria L Kay
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Garen K Anderson
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Justin D Sprick
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas.,Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Caroline A Rickards
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
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25
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Williams JS, Dunford EC, Cheng JL, Moncion K, Valentino SE, Droog CA, Cherubini JM, King TJ, Noguchi KS, Wiley E, Turner JR, Tang A, Al-Khazraji BK, MacDonald MJ. The impact of the 24-h movement spectrum on vascular remodeling in older men and women: a review. Am J Physiol Heart Circ Physiol 2021; 320:H1136-H1155. [PMID: 33449851 DOI: 10.1152/ajpheart.00754.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Aging is associated with increased risk of cardiovascular and cerebrovascular events, which are preceded by early, negative remodeling of the vasculature. Low physical activity is a well-established risk factor associated with the incidence and development of disease. However, recent physical activity literature indicates the importance of considering the 24-h movement spectrum. Therefore, the purpose of this review was to examine the impact of the 24-h movement spectrum, specifically physical activity (aerobic and resistance training), sedentary behavior, and sleep, on cardiovascular and cerebrovascular outcomes in older adults, with a focus on recent evidence (<10 yr) and sex-based considerations. The review identifies that both aerobic training and being physically active (compared with sedentary) are associated with improvements in endothelial function, arterial stiffness, and cerebrovascular function. Additionally, there is evidence of sex-based differences in endothelial function: a blunted improvement in aerobic training in postmenopausal women compared with men. While minimal research has been conducted in older adults, resistance training does not appear to influence arterial stiffness. Poor sleep quantity or quality are associated with both impaired endothelial function and increased arterial stiffness. Finally, the review highlights mechanistic pathways involved in the regulation of vascular and cerebrovascular function, specifically the balance between pro- and antiatherogenic factors, which mediate the relationship between the 24-h movement spectrum and vascular outcomes. Finally, this review proposes future research directions: examining the role of duration and intensity of training, combining aerobic and resistance training, and exploration of sex-based differences in cardiovascular and cerebrovascular outcomes.
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Affiliation(s)
- Jennifer S Williams
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Emily C Dunford
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Jem L Cheng
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Kevin Moncion
- MacStroke Canada, School of Rehabilitation Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Sydney E Valentino
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Connor A Droog
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Joshua M Cherubini
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Trevor J King
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Kenneth S Noguchi
- MacStroke Canada, School of Rehabilitation Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Elise Wiley
- MacStroke Canada, School of Rehabilitation Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Joshua R Turner
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Ada Tang
- MacStroke Canada, School of Rehabilitation Sciences, McMaster University, Hamilton, Ontario, Canada
| | | | - Maureen J MacDonald
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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26
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Shoemaker LN, Wilson LC, Lucas SJE, Machado L, Walker RJ, Cotter JD. Indomethacin markedly blunts cerebral perfusion and reactivity, with little cognitive consequence in healthy young and older adults. J Physiol 2020; 599:1097-1113. [DOI: 10.1113/jp280118] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 11/05/2020] [Indexed: 12/11/2022] Open
Affiliation(s)
- L. N. Shoemaker
- School of Physical Education, Sport and Exercise Sciences University of Otago Dunedin New Zealand
| | - L. C. Wilson
- Department of Medicine Otago Medical School ‐ Dunedin Campus University of Otago Dunedin New Zealand
| | - S. J. E. Lucas
- Department of Physiology University of Otago Dunedin New Zealand
- School of Sport, Exercise and Rehabilitation Sciences College of Life and Environmental Sciences University of Birmingham Birmingham UK
- Centre for Human Brain Health University of Birmingham Birmingham UK
| | - L. Machado
- Department of Psychology University of Otago Dunedin New Zealand
| | - R. J. Walker
- Department of Medicine Otago Medical School ‐ Dunedin Campus University of Otago Dunedin New Zealand
| | - J. D. Cotter
- School of Physical Education, Sport and Exercise Sciences University of Otago Dunedin New Zealand
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27
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Thomas KN, Gibbons TD, Necas M. Letter to the Editor: Imaging Transcranial Doppler Ultrasound: is it giving us an accurate picture of cerebral hemodynamics? Am J Physiol Regul Integr Comp Physiol 2020; 319:R79-R80. [PMID: 32598167 DOI: 10.1152/ajpregu.00134.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Kate N Thomas
- Department of Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Travis D Gibbons
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Martin Necas
- Department of Ultrasound, Waikato Hospital, Hamilton, New Zealand
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28
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van Campen C(LM, Rowe PC, Visser FC. Cerebral Blood Flow Is Reduced in Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients During Mild Orthostatic Stress Testing: An Exploratory Study at 20 Degrees of Head-Up Tilt Testing. Healthcare (Basel) 2020; 8:healthcare8020169. [PMID: 32545797 PMCID: PMC7349207 DOI: 10.3390/healthcare8020169] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/01/2020] [Accepted: 06/10/2020] [Indexed: 12/14/2022] Open
Abstract
Introduction: In a study of 429 adults with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), we demonstrated that 86% had symptoms of orthostatic intolerance in daily life. Using extracranial Doppler measurements of the internal carotid and vertebral arteries during a 30-min head-up tilt to 70 degrees, 90% had an abnormal reduction in cerebral blood flow (CBF). A standard head-up tilt test of this duration might not be tolerated by the most severely affected bed-ridden ME/CFS patients. This study examined whether a shorter 15-min test at a lower 20 degree tilt angle would be sufficient to provoke reductions in cerebral blood flow in severe ME/CFS patients. Methods and results: Nineteen severe ME/CFS patients with orthostatic intolerance complaints in daily life were studied: 18 females. The mean (SD) age was 35(14) years, body surface area (BSA) was 1.8(0.2) m2 and BMI was 24.0(5.4) kg/m2. The median disease duration was 14 (IQR 5–18) years. Heart rate increased, and stroke volume index and end-tidal CO2 decreased significantly during the test (p ranging from <0.001 to <0.0001). The cardiac index decreased by 26(7)%: p < 0.0001. CBF decreased from 617(72) to 452(63) mL/min, a 27(5)% decline. All 19 severely affected ME/CFS patients met the criteria for an abnormal CBF reduction. Conclusions: Using a less demanding 20 degree tilt test for 15 min in severe ME/CFS patients resulted in a mean CBF decline of 27%. This is comparable to the mean 26% decline previously noted in less severely affected patients studied during a 30-min 70 degree head-up tilt. These observations have implications for the evaluation and treatment of severely affected individuals with ME/CFS.
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Affiliation(s)
| | - Peter C. Rowe
- Department of Paediatrics, John Hopkins University School of Medicine, Baltimore, MD 21205, USA;
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29
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Acute exercise-related cognitive effects are not attributable to changes in end-tidal CO2 or cerebral blood velocity. Eur J Appl Physiol 2020; 120:1637-1649. [DOI: 10.1007/s00421-020-04393-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 05/12/2020] [Indexed: 01/20/2023]
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30
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Jarrett CL, Shields KL, Broxterman RM, Hydren JR, Park SH, Gifford JR, Richardson RS. Imaging transcranial Doppler ultrasound to measure middle cerebral artery blood flow: the importance of measuring vessel diameter. Am J Physiol Regul Integr Comp Physiol 2020; 319:R33-R42. [PMID: 32401627 DOI: 10.1152/ajpregu.00025.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cerebral blood flow (CBF) is commonly inferred from blood velocity measurements in the middle cerebral artery (MCA), using nonimaging, transcranial Doppler ultrasound (TCD). However, both blood velocity and vessel diameter are critical components required to accurately determine blood flow, and there is mounting evidence that the MCA is vasoactive. Therefore, the aim of this study was to employ imaging TCD (ITCD), utilizing color flow images and pulse wave velocity, as a novel approach to measure both MCA diameter and blood velocity to accurately quantify changes in MCA blood flow. ITCD was performed at rest in 13 healthy participants (7 men/6 women; 28 ± 5 yr) with pharmaceutically induced vasodilation [nitroglycerin (NTG), 0.8 mg] and without (CON). Measurements were taken for 2 min before and for 5 min following NTG or sham delivery (CON). There was more than a fivefold, significant, fall in MCA blood velocity in response to NTG (∆-4.95 ± 4.6 cm/s) compared to negligible fluctuation in CON (∆-0.88 ± 4.7 cm/s) (P < 0.001). MCA diameter increased significantly in response to NTG (∆0.09 ± 0.04 cm) compared with the basal variation in CON (∆0.00 ± 0.04 cm) (P = 0.018). Interestingly, the product of the NTG-induced fall in MCA blood velocity and increase in diameter was a significant increase in MCA blood flow following NTG (∆144 ± 159 ml/min) compared with CON (∆-5 ± 130 ml/min) (P = 0.005). These juxtaposed findings highlight the importance of measuring both MCA blood velocity and diameter when assessing CBF and document ITCD as a novel approach to achieve this goal.
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Affiliation(s)
- Catherine L Jarrett
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Katherine L Shields
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Ryan M Broxterman
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Jay R Hydren
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Soung Hun Park
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Jayson R Gifford
- Department of Exercise Sciences, Brigham Young University, Provo, Utah
| | - Russell S Richardson
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah
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31
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Favre ME, Lim V, Falvo MJ, Serrador JM. Cerebrovascular reactivity and cerebral autoregulation are improved in the supine posture compared to upright in healthy men and women. PLoS One 2020; 15:e0229049. [PMID: 32119678 PMCID: PMC7051088 DOI: 10.1371/journal.pone.0229049] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 01/28/2020] [Indexed: 12/04/2022] Open
Abstract
Cerebrovascular reactivity and cerebral autoregulation are two major mechanisms that regulate cerebral blood flow. Both mechanisms are typically assessed in either supine or seated postures, but the effects of body position and sex differences remain unclear. This study examined the effects of body posture (supine vs. seated vs. standing) on cerebrovascular reactivity during hyper and hypocapnia and on cerebral autoregulation during spontaneous and slow-paced breathing in healthy men and women using transcranial Doppler ultrasonography of the middle cerebral artery. Results indicated significantly improved cerebrovascular reactivity in the supine compared with seated and standing postures (supine = 3.45±0.67, seated = 2.72±0.53, standing = 2.91±0.62%/mmHg, P<0.0167). Similarly, cerebral autoregulatory measures showed significant improvement in the supine posture during slow-paced breathing. Transfer function measures of gain significantly decreased and phase significantly increased in the supine posture compared with seated and standing postures (gain: supine = 1.98±0.56, seated = 2.37±0.53, standing = 2.36±0.71%/mmHg; phase: supine = 59.3±21.7, seated = 39.8±12.5, standing = 36.5±9.7°; all P<0.0167). In contrast, body posture had no effect on cerebral autoregulatory measures during spontaneous breathing. Men and women had similar cerebrovascular reactivity and similar cerebral autoregulation during both spontaneous and slow-paced breathing. These data highlight the importance of making comparisons within the same body position to ensure there is not a confounding effect of posture.
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Affiliation(s)
- Michelle E. Favre
- Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America
| | - Valerie Lim
- Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America
| | - Michael J. Falvo
- Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America
- Department of Physical Medicine and Rehabilitation, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America
- Department of Veterans Affairs, War Related Illness and Injury Study Center, East Orange, New Jersey, United States of America
| | - Jorge M. Serrador
- Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America
- Department of Cardiovascular Electronics, National University of Ireland Galway, Galway, Ireland
- * E-mail:
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32
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Junejo RT, May S, Alsalahi S, Alali M, Ogoh S, Fisher JP. Cerebrovascular carbon dioxide reactivity and flow-mediated dilation in young healthy South Asian and Caucasian European men. Am J Physiol Heart Circ Physiol 2020; 318:H756-H763. [PMID: 32083976 DOI: 10.1152/ajpheart.00641.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
South Asians living in the United Kingdom have a 1.5-fold greater risk of ischemic stroke than the general population. Impaired cerebrovascular carbon dioxide (CO2) reactivity is an independent predictor of ischemic stroke and cardiovascular mortality. We sought to test the hypothesis that cerebrovascular CO2 reactivity is reduced in South Asians. Middle cerebral artery blood velocity (MCA Vm) was measured at rest and during stepwise changes in end-tidal partial pressure of CO2 (PETCO2) in South Asian (n = 16) and Caucasian European (n = 18) men who were young (~20 yr), healthy, and living in the United Kingdom. Incremental hypercapnia was delivered via the open-circuit steady-state method, with stages of 4 and 7% CO2 (≈21% oxygen, nitrogen balanced). Cerebrovascular CO2 reactivity was calculated as the change in MCA Vm relative to the change in PETCO2. MCA Vm was not different in South Asians [59 (9) cm/s, mean (standard deviation)] and Caucasian Europeans [61 (12) cm/s; P > 0.05]. Similarly, cerebrovascular CO2 reactivity was not different between the groups [South Asian 2.53 (0.76) vs. Caucasian European 2.61 (0.81) cm·s-1·mmHg-1; P > 0.05]. Brachial artery flow-mediated dilation was lower in South Asians [5.48 (2.94)%] compared with Caucasian Europeans [7.41 (2.28)%; P < 0.05]; however, when corrected for shear rate no between-group differences in flow-mediated dilation were observed (P > 0.05). Flow-mediated dilation was not correlated with cerebrovascular CO2 reactivity measures. In summary, cerebrovascular CO2 reactivity and flow-mediated dilation corrected for shear rate are preserved in young healthy South Asian men living in the United Kingdom.NEW & NOTEWORTHY Previous reports have identified an increased risk of ischemic stroke and peripheral endothelial dysfunction in South Asians compared with Caucasian Europeans. The main finding of this study is that cerebrovascular carbon dioxide reactivity (an independent predictor of ischemic stroke) is not different in healthy young South Asian and Caucasian European men.
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Affiliation(s)
- Rehan T Junejo
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom.,Liverpool Centre for Cardiovascular Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Sophie May
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Sultan Alsalahi
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Mohammad Alali
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Saitama, Japan
| | - James P Fisher
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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33
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van Campen C(LM, Verheugt FW, Rowe PC, Visser FC. Cerebral blood flow is reduced in ME/CFS during head-up tilt testing even in the absence of hypotension or tachycardia: A quantitative, controlled study using Doppler echography. Clin Neurophysiol Pract 2020; 5:50-58. [PMID: 32140630 PMCID: PMC7044650 DOI: 10.1016/j.cnp.2020.01.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 12/05/2019] [Accepted: 01/02/2020] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE The underlying hypothesis in orthostatic intolerance (OI) syndromes is that symptoms are associated with cerebral blood flow (CBF) reduction. Indirect CBF measurements (transcranial Doppler flow velocities), provide inconsistent support of this hypothesis. The aim of the study was to measure CBF during a 30 min head-up tilt test (HUT), using Doppler flow imaging of carotid and vertebral arteries, in individuals with chronic fatigue syndrome/myalgic encephalomyelitis (ME/CFS), a condition with a high prevalence of OI. METHODS 429 ME/CFS patients were studied: 247 had a normal heart rate (HR) and blood pressure (BP) response to HUT, 62 had delayed orthostatic hypotension (dOH), and 120 had postural orthostatic tachycardia syndrome (POTS). We also studied 44 healthy controls (HC). CBF measurements were made at mid-tilt and end-tilt. Before mid-tilt, we administered a verbal questionnaire to ascertain for 15 OI symptoms. RESULTS End-tilt CBF reduction was 7% in HC versus 26% in the overall ME/CFS group, 24% in patients with a normal HR/BP response, 28% in those with dOH, and 29% in POTS patients (all P < .0005). Using a lower limit of normal of 2SD of CBF reduction in HC (13% reduction), 82% of patients with normal HR/BP response, 98% with dOH and 100% with POTS showed an abnormal CBF reduction. There was a linear correlation of summed OI symptoms with the degree of CBF reduction at mid-tilt (P < .0005). CONCLUSIONS During HUT, extracranial Doppler measurements demonstrate that CBF is reduced in ME/CFS patients with POTS, dOH, and even in those without HR/BP abnormalities. SIGNIFICANCE This study shows that orthostatic intolerance symptoms are related to CBF reduction, and that the majority of ME/CFS patients (90%) show an abnormal cerebral flow reduction during orthostatic stress testing. This may have implications for the diagnosis and treatment of ME/CFS patients.
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Affiliation(s)
| | - Freek W.A. Verheugt
- Department of Cardiology, Onze Lieve Vrouwe Gasthuis (OLVG), Oosterpark 9, 1091 AC Amsterdam, The Netherlands
| | - Peter C. Rowe
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Frans C. Visser
- Stichting CardioZorg, Planetenweg 5, 2132 HN Hoofddorp, The Netherlands
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34
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Hlavati M, Buljan K, Tomić S, Horvat M, Butković-Soldo S. Impaired cerebrovascular reactivity in chronic obstructive pulmonary disease. Acta Neurol Belg 2019; 119:567-575. [PMID: 31215005 DOI: 10.1007/s13760-019-01170-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 06/11/2019] [Indexed: 11/27/2022]
Abstract
Impaired cerebrovascular reactivity (CVR) is associated with stroke. Cerebrovascular diseases are common comorbidity in chronic obstructive pulmonary disease (COPD) patients. The aim of our study was to quantify CVR in the anterior and posterior cerebral circulation during voluntary breath-holding in COPD patients according to airflow limitation severity. In this cross-sectional study, we compared 90 COPD patients without previous cerebrovascular disease and 30 age- and sex-matched healthy volunteers (mean age 67 ± 7.9, 87 males). Using transcranial Doppler ultrasound and breath-holding index (BHI), we analysed baseline mean flow velocities (MFV) and CVR of middle cerebral artery (MCA) and basilar artery (BA). Our results demonstrated that COPD patients had lower baseline MFV of both MCA and BA than controls. COPD patients had significantly lower BHImMCA and BHImBA than controls (0.8 and 0.7 versus 1.24 and 1.07, respectively; p < 0.001). With the severity of airflow obstruction, there were significant declines of BHImMCA and BHImBA in mild (0.94 and 0.83), moderate (0.8 and 0.7) and severe to very severe COPD (0.7 and 0.6), respectively (p < 0.001). For all participants, we found a significant and positive correlation between forced expiratory volume in one second (FEV1) and BHImMCA (Rho = 0.761, p < 0.001) and between FEV1 and BHImBA (Rho = 0.409, p < 0.001). COPD patients have impaired CVR in anterior and posterior cerebral circulation. Impairment of CVR increase with the airflow limitation severity. CVR is an appropriate marker to identify vulnerable COPD subjects at high risk to develop cerebrovascular disease. Prospective studies are needed for further evaluation.
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Affiliation(s)
- Marina Hlavati
- Department for Diagnostic and Therapeutical Procedures, Neurology Unit, General Hospital Našice, Bana Jelačića 10, 31500, Našice, Croatia.
- Faculty of Medicine Osijek, University Josip Juraj Strossmayer Osijek, Josipa Huttlera 4, 31000, Osijek, Croatia.
| | - Krunoslav Buljan
- Neurology Clinic, Clinic Hospital Centre Osijek, Josipa Huttlera 4, 31000, Osijek, Croatia
| | - Svetlana Tomić
- Neurology Clinic, Clinic Hospital Centre Osijek, Josipa Huttlera 4, 31000, Osijek, Croatia
| | - Mirjana Horvat
- Department of Internal Medicine, Pulmonology Unit, General Hospital Našice, Bana Jelačića 10, 31500, Našice, Croatia
| | - Silva Butković-Soldo
- Faculty of Medicine Osijek, University Josip Juraj Strossmayer Osijek, Josipa Huttlera 4, 31000, Osijek, Croatia
- Neurology Clinic, Clinic Hospital Centre Osijek, Josipa Huttlera 4, 31000, Osijek, Croatia
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35
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Miller KB, Howery AJ, Rivera-Rivera LA, Johnson SC, Rowley HA, Wieben O, Barnes JN. Age-Related Reductions in Cerebrovascular Reactivity Using 4D Flow MRI. Front Aging Neurosci 2019; 11:281. [PMID: 31680935 PMCID: PMC6811507 DOI: 10.3389/fnagi.2019.00281] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 10/01/2019] [Indexed: 12/12/2022] Open
Abstract
Cerebrovascular reactivity (CVR), is important for determining future risk of cerebrovascular disease. It is unclear if primary aging is associated with reductions in CVR because previous studies often include participants with vascular risk factors. Additionally, the inconsistency in the literature may be due to the inherent difficulty in quantifying intracranial cerebral blood flow and CVR. To address these limitations, we determined the effect of age on CVR in the large intracranial vessels in adults with low vascular risk using state-of-the-art MRI techniques. We also determined if the effect of age on CVR was sex-specific. Young (n = 20; 25 ± 3 years) and older (n = 19; 61 ± 5 years) healthy, physically active adults participated in the study. CVR was measured in response to hypercapnia using 4D flow MRI, which allows for simultaneous angiographic and quantitative blood flow measurements in the intracranial arteries. Older adults had lower global CVR and CVR in multiple intracranial arteries [right and left internal carotid arteries (ICA), right and left middle cerebral arteries (MCA), and basilar artery (BA)] compared with young adults (p < 0.05 for all). In addition, the MCA dilated significantly in response to hypercapnia in young (p < 0.05), but not older adults. Young men demonstrated higher global CVR and CVR in multiple intracranial arteries (ICAs, MCAs, and BA) compared with young women and older men (p < 0.05 for both); however, CVR did not differ between young women and older women. Our results demonstrate that, using 4D flow MRI, primary aging is associated with lower CVR in adults with low vascular risk. In addition, the effect of age on CVR may be driven by men. The 4D flow MRI technique may provide a promising new alternative to measure cerebrovascular physiology without the limitations of commonly used techniques. Future studies could utilize this MRI technique to examine interventions to maintain CVR with advancing age. This study was registered under clinicaltrials.gov # NCT02840851.
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Affiliation(s)
- Kathleen B Miller
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, WI, United States
| | - Anna J Howery
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, WI, United States
| | - Leonardo A Rivera-Rivera
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Sterling C Johnson
- Wisconsin Alzheimer's Disease Research Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States.,William S. Middleton Memorial Veterans Hospital, Geriatric Research Education and Clinical Center, Madison, WI, United States
| | - Howard A Rowley
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States.,Wisconsin Alzheimer's Disease Research Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Oliver Wieben
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Jill N Barnes
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, WI, United States
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36
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Shoemaker LN, Wilson LC, Lucas SJE, Machado L, Cotter JD. Cerebrovascular regulation is not blunted during mental stress. Exp Physiol 2019; 104:1678-1687. [PMID: 31465595 DOI: 10.1113/ep087832] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 08/22/2019] [Indexed: 01/08/2023]
Abstract
NEW FINDINGS What is the central question of the study? What are the effects of acute mental stress on the mechanisms regulating cerebral blood flow? What is the main finding and its importance? The major new findings are as follows: (i) high mental stress and hypercapnia had an interactive effect on mean middle cerebral artery blood velocity; (ii) high mental stress altered the regulation of cerebral blood flow; (iii) the increased cerebrovascular hypercapnic reactivity was not driven by changes in mean arterial pressure alone; and (iv) this increased perfusion with mental stress appeared not to be justified functionally by an increase in oxygen demand (as determined by near-infrared spectroscopy-derived measures). ABSTRACT In this study, we examined the effects of acute mental stress on cerebrovascular function. Sixteen participants (aged 23 ± 4 years; five female) were exposed to low and high mental stress using simple arithmetic (counting backwards from 1000) and more complex arithmetic (serial subtraction of 13 from a rapidly changing four-digit number), respectively. During consecutive conditions of baseline, low stress and high stress, end-tidal partial pressure of CO2 ( P ET , C O 2 ) was recorded at normocapnia (37 ± 3 mmHg) and clamped at two elevated levels (P < 0.01): 41 ± 1 and 46 ± 1 mmHg. Mean right middle cerebral artery blood velocity (MCAvmean ; transcranial Doppler ultrasound), right prefrontal cortex haemodynamics (near-infrared spectroscopy) and mean arterial blood pressure (MAP; finger photoplethysmography) were measured continuously. Cerebrovascular hypercapnic reactivity (ΔMCAvmean /Δ P ET , C O 2 ), cerebrovascular conductance (CVC; MCAvmean /MAP), CVC CO2 reactivity (ΔCVC/Δ P ET , C O 2 ) and total peripheral resistance (MAP/cardiac output) were calculated. Acute high mental stress increased MCAvmean by 7 ± 7%, and more so at higher P ET , C O 2 (32 ± 10%; interaction, P = 0.03), illustrating increased sensitivity to CO2 (i.e. its major regulator). High mental stress also increased MAP (17 ± 9%; P ≤ 0.01), coinciding with increased near-infrared spectroscopy-derived prefrontal haemoglobin volume and saturation measures. High mental stress elevated both cerebrovascular hypercapnic and conductance reactivities (main effect of stress, P ≤ 0.04). These findings indicate that the cerebrovascular response to acute high mental stress results in a coordinated regulation between multiple processes.
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Affiliation(s)
- Leena N Shoemaker
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Luke C Wilson
- Department of Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Samuel J E Lucas
- Department of Physiology, University of Otago, Dunedin, New Zealand.,School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, UK.,Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Liana Machado
- Department of Psychology, University of Otago, Dunedin, New Zealand
| | - James D Cotter
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
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Shoemaker LN, Wilson LC, Lucas SJE, Machado L, Thomas KN, Cotter JD. Swimming-related effects on cerebrovascular and cognitive function. Physiol Rep 2019; 7:e14247. [PMID: 31637867 PMCID: PMC6803778 DOI: 10.14814/phy2.14247] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 09/06/2019] [Indexed: 02/07/2023] Open
Abstract
Both acute and regular exercise influence vascular and cognitive function. Upright aquatic exercise increases mean middle cerebral artery blood velocity (MCAvmean ) and has been suggested as favorable for cerebrovascular adaptations. However, MCAvmean has not been reported during swimming. Thus, we examined the cerebrovascular and cognitive effects of swimming. Ten land-based athletes (22 ± 5 years) and eight swimmers (19 ± 1 years) completed three cognitive tasks and four conditions that were used to independently and collectively delineate the swimming-related factors (i.e., posture, immersion, CO2 retention [end-tidal CO2 ; PETCO2 ], and motor involvement). Measurements of MCAvmean and PETCO2 were taken throughout each condition. Prone posture increased MCAvmean by 11% (P < 0.01 vs. upright land). Water immersion independently increased MCAvmean when upright (12%; P < 0.01) but not prone (P = 0.76). The consequent rise in PETCO2 during head-out, breast-stroke swimming (50% heart rate range) independently increased MCAvmean by 14% (P < 0.01), while the motor involvement of swimming per se did not significantly change MCAvmean (P = 0.32). While accounting for sex, swimmers had ~17% lower MCAvmean during all rest conditions (P ≤ 0.05). However, in a subset of participants, both groups had similar internal carotid artery diameters (P = 0.99) and velocities (P = 0.97). Water immersion per se did not alter cognition (P ≥ 0.15), but 20 min of moderate-intensity swimming improved visuomotor performance by 4% (P = 0.03), regardless of athlete group (P = 0.12). In conclusion, breast-stroke swimming increased MCAvmean mostly due to postural and PETCO2 effects, with minimal contributions from water immersion or motor activity. Lastly, swimming improved cognitive functioning acutely, regardless of athlete group. Future research should explore the chronic effects of swimming on cerebrovascular function and cognition, particularly in aging.
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Affiliation(s)
- Leena N. Shoemaker
- School of Physical Education, Sport and Exercise SciencesUniversity of OtagoDunedinNew Zealand
- Department of MedicineDunedin School of MedicineUniversity of OtagoDunedinNew Zealand
- Department of PsychologyUniversity of OtagoDunedinNew Zealand
| | - Luke C. Wilson
- Department of MedicineDunedin School of MedicineUniversity of OtagoDunedinNew Zealand
| | - Samuel J. E. Lucas
- Department of PhysiologyUniversity of OtagoDunedinNew Zealand
- School of Sport, Exercise and Rehabilitation SciencesCollege of Life and Environmental SciencesUniversity of BirminghamBirminghamUK
- Centre for Human Brain HealthUniversity of BirminghamBirminghamUK
| | - Liana Machado
- Department of PsychologyUniversity of OtagoDunedinNew Zealand
| | - Kate N. Thomas
- Department of Surgical SciencesDunedin School of MedicineUniversity of OtagoDunedinNew Zealand
| | - James D. Cotter
- School of Physical Education, Sport and Exercise SciencesUniversity of OtagoDunedinNew Zealand
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38
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Al‐Khazraji BK, Badrov MB, Kadem M, Lingum NR, Birmingham TB, Shoemaker JK. Exploring Cerebrovascular Function in Osteoarthritis: "Heads-up". Physiol Rep 2019; 7:e14212. [PMID: 31660705 PMCID: PMC6817995 DOI: 10.14814/phy2.14212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/26/2019] [Accepted: 07/30/2019] [Indexed: 11/24/2022] Open
Abstract
Individuals with osteoarthritis (OA) are at greater risk of cardiovascular and cerebrovascular incidents; yet, cerebrovascular control remains uncharacterized. Our primary outcome was to acquire cerebrovascular control metrics in patients with OA and compare measures to healthy control adults (CTL) without OA or cardiovascular complications. Our primary covariate was a 10-year risk factor for cardiovascular and stroke incidents, and secondary covariates were other cardiovascular disease risk factors (i.e., body mass index, carotid intima media thickness, and brachial flow-mediated dilation). Our secondary outcomes were to assess anatomical and functional changes that may be related to cerebrovascular reactivity were also acquired such as white matter lesion volume and brief cognitive assessments. In 25 adults (n = 13 CTL, n = 12 OA), under hypercapnia, magnetic resonance imaging (3T) was used to acquire a "Global Cerebrovascular Reactivity" index across the larger intracranial cerebral arteries and white matter lesions, and transcranial Doppler was used for both middle cerebral artery hemodynamic responses to hypercapnia and to assess autoregulation via a sit-to-stand task. Compared to CTL, OA had lower "Global Cerebrovascular Reactivity" index responses to hypercapnia, autoregulatory responses, and greater white matter lesions (P < 0.05). These differences persisted after covarying for the outlined primary and secondary covariates. Patients with OA, in the absence of known cardiovascular disease, can exhibit pre-clinical and impaired (compared to CTL) peripheral and cerebrovascular control metrics.
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Affiliation(s)
- Baraa K. Al‐Khazraji
- School of Kinesiology, Faculty of Health SciencesWestern UniversityLondonOntarioCanada
- Bone and Joint InstituteWestern UniversityLondonOntarioCanada
| | - Mark B. Badrov
- School of Kinesiology, Faculty of Health SciencesWestern UniversityLondonOntarioCanada
| | - Mason Kadem
- Brain and Mind InstituteWestern UniversityLondonOntarioCanada
| | - Navena R. Lingum
- School of Kinesiology, Faculty of Health SciencesWestern UniversityLondonOntarioCanada
| | - Trevor B. Birmingham
- School of Physical TherapyFaculty of Health SciencesWestern OntarioLondon, OntarioCanada
- Bone and Joint InstituteWestern UniversityLondonOntarioCanada
| | - Joel Kevin Shoemaker
- School of Kinesiology, Faculty of Health SciencesWestern UniversityLondonOntarioCanada
- Bone and Joint InstituteWestern UniversityLondonOntarioCanada
- Department of Physiology and Pharmacology, Schulich School of Medicine and DentistryWestern UniversityLondonOntarioCanada
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Hoiland RL, Fisher JA, Ainslie PN. Regulation of the Cerebral Circulation by Arterial Carbon Dioxide. Compr Physiol 2019; 9:1101-1154. [DOI: 10.1002/cphy.c180021] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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40
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Kaur J, Vranish JR, Barbosa TC, Washio T, Young BE, Stephens BY, Brothers RM, Ogoh S, Fadel PJ. Regulation of Regional Cerebral Blood Flow During Graded Reflex-Mediated Sympathetic Activation via Lower Body Negative Pressure. J Appl Physiol (1985) 2018; 125:1779-1786. [PMID: 30188801 PMCID: PMC10392631 DOI: 10.1152/japplphysiol.00623.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of the sympathetic nervous system in cerebral blood flow (CBF) regulation remains unclear. Previous studies have primarily measured middle cerebral artery blood velocity to assess CBF. Recently, there has been a transition towards measuring internal carotid artery (ICA) and vertebral artery (VA) blood flow using duplex Doppler ultrasound. Given that the VA supplies autonomic control centers in the brainstem, we hypothesized that graded sympathetic activation via lower body negative pressure (LBNP) would reduce ICA but not VA blood flow. ICA and VA blood flow were measured during two protocols: Protocol-1, low-to-moderate LBNP (-10, -20, -30, -40 Torr) and Protocol-2, moderate-to-high LBNP (-30, -50, -70 Torr). ICA and VA blood flow, diameter, and blood velocity were unaffected up to -40 LBNP. However, -50 and -70 LBNP evoked reductions in ICA and VA blood flow (e.g., -70 LBNP: %∆VA-baseline= -27.6±3.0) that were mediated by decreases in both diameter and velocity (e.g., -70 LBNP: %∆VA-baseline diameter= -7.5±1.9 and %∆VA-baseline velocity= -13.6±1.7), which were comparable between vessels. Since hyperventilation during -70 LBNP reduced PETCO2, this decrease in PETCO2 was matched via voluntary hyperventilation. Reductions in ICA and VA blood flow during hyperventilation alone were significantly smaller than during -70 LBNP and were primarily mediated by decreases in velocity (%∆VA-baseline velocity= -8.6±2.4; %∆VA-baseline diameter= -0.05±0.56). These data demonstrate that both ICA and VA were unaffected by low-to-moderate sympathetic activation, whereas robust reflex-mediated sympatho-excitation caused similar magnitudes of vasoconstriction in both arteries. Thus, contrary to our hypothesis, the ICA was not preferentially vasoconstricted by sympathetic activation.
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Affiliation(s)
- Jasdeep Kaur
- Department of Kinesiology, University of Texas at Arlington, United States
| | - Jennifer R Vranish
- Department of Kinesiology, University of Texas at Arlington, United States
| | - Thales C Barbosa
- Department of Kinesiology, University of Texas at Arlington, United States
| | - Takuro Washio
- Department of Biomedical Engineering, Toyo University
| | | | | | | | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Japan
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, United States
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Schulz JM, Al-Khazraji BK, Shoemaker JK. Sodium nitroglycerin induces middle cerebral artery vasodilatation in young, healthy adults. Exp Physiol 2018; 103:1047-1055. [PMID: 29766604 PMCID: PMC6099468 DOI: 10.1113/ep087022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/08/2018] [Indexed: 01/03/2023]
Abstract
NEW FINDINGS What is the central question of this study? Nitric oxide causes dilatation in peripheral vessels; however, whether nitric oxide affects basal cerebral artery dilatation has not been explored. What is the main finding and its importance? This study demonstrated that vasodilatation occurs in the right middle cerebral artery in response to exogenous nitric oxide. However, blood velocity decreased and, therefore, overall cerebral blood flow remained unchanged. This study provides new insight into the role of nitric oxide in cerebral blood flow control. ABSTRACT Recent evidence indicates that basal cerebral conduit vessels dilate with hypercapnia, with a nitric oxide (NO) mechanism explaining one way in which parenchymal cerebral arterioles dilate. However, whether NO affects basal cerebral artery dilatation remains unknown. This study quantified the effect of an exogenous NO donor [sodium nitroglycerin (NTG); 0.4 mg sublingual spray] on the right middle cerebral artery (rMCA) cross-sectional area (CSA), blood velocity and overall blood flow. Measures of vessel CSA (7 T magnetic resonance imaging) and MCA blood velocity (transcranial Doppler ultrasound) were made at baseline (BL) and after exogenous NTG or placebo (PLO) administration in young, healthy individuals (n = 10, two males, age range 20-23 years). The CSA increased in the rMCA [BL, 5.2 ± 1.2 mm2 ; PLO, 5.4 ± 1.5 mm2 ; NTG, 6.6 ± 1.5 mm2 , P < 0.05; mean ± SD]. Concurrently, rMCA blood velocity decreased from BL during NTG compared with PLO (BL, 67 ± 10 cm s-1 ; PLO, 62 ± 10 cm s-1 ; NTG, 59 ± 9.3 cm s-1 , P < 0.05; mean ± SD]. However, total MCA blood flow did not change with NTG or PLO [BL, 221 ± 37.4 ml min-1 ; PLO, 218 ± 35.0 ml min-1 ; NTG, 213 ± 46.4 ml min-1 ). Therefore, exogenous NO mediates a dilatory response in the rMCA, but not in its downstream vascular bed.
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Affiliation(s)
- Jenna M Schulz
- School of Physical Therapy, Department of Health Sciences, Western University, London, ON, Canada
| | - Baraa K Al-Khazraji
- School of Kinesiology, Department of Health Sciences, Western University, London, ON, Canada
| | - J Kevin Shoemaker
- Department of Physiology and Pharmacology, Western University, London, ON, Canada.,School of Kinesiology, Department of Health Sciences, Western University, London, ON, Canada
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