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Abdali K, Chen X, Ross S, Davis S, Zhou Z, Mallet RT, Shi X. Mechanisms maintaining cerebral perfusion during systemic hypotension are impaired in elderly adults. Exp Biol Med (Maywood) 2023; 248:2464-2472. [PMID: 38057956 PMCID: PMC10903242 DOI: 10.1177/15353702231209416] [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: 08/02/2023] [Accepted: 09/11/2023] [Indexed: 12/08/2023] Open
Abstract
Postural hypotension abruptly lowers cerebral perfusion, producing unsteadiness which worsens with aging. This study addressed the hypothesis that maintenance of cerebral perfusion weakens in the elderly due to less effective cerebrovascular autoregulation and systemic cardiovascular responses to hypotension. In healthy elderly (n = 13, 68 ± 1 years) and young (n = 13, 26 ± 1 years) adults, systemic hypotension was induced by rapid deflation of bilateral thigh cuffs after 3-min suprasystolic occlusion, while heart rate (HR), mean arterial pressure (MAP), and blood flow velocity of the middle cerebral artery (VMCA) were recorded. VMCA/MAP indexed cerebrovascular conductance (CVC). Durations and rates of recovery of MAP and VMCA from their respective postdeflation nadirs were compared between the groups. Thigh-cuff deflation elicited similar hypotension and cerebral hypoperfusion in the elderly and young adults. However, the time elapsed (TΔ) from cuff deflation to the nadirs of MAP and VMCA, and the time for full recovery (TR) from nadirs to baselines were significantly prolonged in the elderly subjects. The response rates of HR (ΔHR, i.e. cardiac factor), MAP (ΔMAP, i.e. vasomotor factor), and CVC following cuff deflation were significantly slower in the elderly. Collectively, the response rates of the cardiac, vasomotor, and CVC factors largely explained TRVMCA. However, the TRVMCA/ΔMAP slope (-3.0 ± 0.9) was steeper (P = 0.046) than the TRVMCA/ΔHR slope (-1.1 ± 0.4). The TRVMCA/ΔCVC slope (-2.4 ± 0.6) was greater (P = 0.072) than the TRVMCA/ΔHR slope, but did not differ from the TRVMCA/ΔMAP slope (P = 0.52). Both cerebrovascular autoregulatory and systemic mechanisms contributed to cerebral perfusion recovery during systemic hypotension, and the vasomotor factor was predominant over the cardiac factor. Recovery from cerebral hypoperfusion was slower in the elderly adults because of the age-diminished rates of the CVC response and cardiovascular reflex regulation. Systemic vasoconstriction predominated over increased HR for restoring cerebral perfusion after abrupt onset of systemic hypotension.
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Affiliation(s)
- Kulsum Abdali
- Departments of Pharmacology and Neuroscience, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Xiaoan Chen
- Departments of Pharmacology and Neuroscience, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
- Jishou University, Jishou 416000, China
| | - Sarah Ross
- Departments of Internal Medicine, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Sandra Davis
- Departments of Internal Medicine, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Zhengyang Zhou
- Departments of Biostatistics & Epidemiology, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Robert T Mallet
- Departments of Physiology and Anatomy, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Xiangrong Shi
- Departments of Pharmacology and Neuroscience, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA
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Whitaker AA, Vidoni ED, Montgomery RN, Carter K, Struckle K, Billinger SA. Force sensor reduced measurement error compared with verbal command during sit-to-stand assessment of cerebral autoregulation. Physiol Rep 2023; 11:e15750. [PMID: 37308311 PMCID: PMC10260377 DOI: 10.14814/phy2.15750] [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: 03/17/2023] [Revised: 05/12/2023] [Accepted: 05/28/2023] [Indexed: 06/14/2023] Open
Abstract
Current methods estimate the time delay (TD) before the onset of dynamic cerebral autoregulation (dCA) from verbal command to stand. A force sensor used during a sit-to-stand dCA measure provides an objective moment an individual stands (arise-and-off, AO). We hypothesized that the detection of AO would improve the accuracy of TD compared with estimation. We measured middle cerebral artery blood velocity (MCAv) and mean arterial pressure (MAP) for 60 s sitting followed by 2-min standing, three times separated by 20 min. TD was calculated as the time from: (1) verbal command and (2) AO, until an increase in cerebrovascular conductance index (CVCi = MCAv/MAP). Sixty-five participants were enrolled: young adults (n = 25), older adults (n = 20), and individuals post-stroke (n = 20). The TD calculated from AO (x ¯ $$ \overline{x} $$ = 2.98 ± 1.64 s) was shorter than TD estimated from verbal command (x ¯ $$ \overline{x} $$ = 3.35 ± 1.72 s, η2 = 0.49, p < 0.001), improving measurement error by ~17%. TD measurement error was not related to age or stroke. Therefore, the force sensor provided an objective method to improve the calculation of TD compared with current methods. Our data support using a force sensor during sit-to-stand dCA measures in adults across the lifespan and post-stroke.
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Affiliation(s)
- Alicen A. Whitaker
- Department of Physical Therapy, Rehabilitation Science, and Athletic TrainingUniversity of Kansas Medical CenterKansas CityKansasUSA
- Department of Physical Medicine and RehabilitationMedical College of WisconsinMilwaukeeWisconsinUSA
- Cardiovascular CenterMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Eric D. Vidoni
- University of Kansas Alzheimer's Disease Research CenterFairwayKansasUSA
- Department of NeurologyUniversity of Kansas Medical CenterKansas CityKansasUSA
| | - Robert N. Montgomery
- Department of Biostatistics & Data ScienceUniversity of Kansas Medical CenterKansas CityKansasUSA
| | - Kailee Carter
- Department of Physical Therapy, Rehabilitation Science, and Athletic TrainingUniversity of Kansas Medical CenterKansas CityKansasUSA
| | - Katelyn Struckle
- Department of Physical Therapy, Rehabilitation Science, and Athletic TrainingUniversity of Kansas Medical CenterKansas CityKansasUSA
| | - Sandra A. Billinger
- University of Kansas Alzheimer's Disease Research CenterFairwayKansasUSA
- Department of NeurologyUniversity of Kansas Medical CenterKansas CityKansasUSA
- Department of Physical Medicine and RehabilitationUniversity of Kansas Medical CenterKansas CityKansasUSA
- Department of Cell Biology and PhysiologyUniversity of Kansas Medical CenterKansas CityKansasUSA
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3
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Dumančić D, Stupin A, Kožul M, Šerić V, Kibel A, Goswami N, Brix B, Debeljak Ž, Scitovski R, Drenjančević I. Increased cerebral vascular resistance underlies preserved cerebral blood flow in response to orthostasis in humans on a high-salt diet. Eur J Appl Physiol 2023; 123:923-933. [PMID: 36598577 DOI: 10.1007/s00421-022-05124-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 12/20/2022] [Indexed: 01/05/2023]
Abstract
Cerebral blood flow autoregulation protects brain tissue from blood pressure variations and maintains cerebral perfusion pressure by changes in vascular resistance. High salt (HS) diet impairs endothelium-dependent vasodilation in many vascular beds, including cerebral microcirculation, and may affect vascular resistance. The aim of present study was to determine if 7-day HS diet affected the reactivity of middle cerebral artery (MCA) to orthostatic challenge in healthy human individuals, and if autoregulatory mechanisms and sympathetic neural regulation were involved in this phenomenon.Twenty-seven persons participated in study (F:21, M:6, age range 19-24). Participants consumed 7-day low-salt (LS) diet (< 2.3 g kitchen salt/day) and afterwards 7-day HS diet (> 11.2 g kitchen salt/day). Blood and urine analysis and anthropometric measurements were performed after each diet. Arterial blood pressure, heart rate and heart rate variability, and cerebral and systemic hemodynamic parameters were recorded simultaneously with transcranial Doppler ultrasound and The Task Force® Monitor in response to orthostatic test.Participants remained normotensive during HS diet. Following both, the LS and HS dietary protocols, mean cerebral blood flow (CBF), as well as the velocity time integral and diastolic blood pressure decreased, and cerebral pulsatility index increased after rising up. Importantly, cerebrovascular resistance significantly increased in response to orthostasis only after HS diet. Urine concentration of noradrenaline and vanillylmandelic acid, baroreflex sensitivity (BRS), and sympathetic neural control was significantly decreased in HS diet.Results suggest that CBF in response to orthostatic test was preserved in HS condition due to altered vascular reactivity of MCA, with increased cerebrovascular resistance and blunted BRS and sympathetic activity.
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Affiliation(s)
- Dijana Dumančić
- Department of Physiology and Immunology, Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, J. Huttlera 4, 31000, Osijek, Croatia
- Department of Diagnostic and Interventional Radiology, University Hospital Centre Osijek, J. Huttlera 4, 31000, Osijek, Croatia
| | - Ana Stupin
- Department of Physiology and Immunology, Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, J. Huttlera 4, 31000, Osijek, Croatia
| | - Maja Kožul
- Department of Dermatology and Venereology, University Hospital Centre Osijek, J. Huttlera 4, 31000, Osijek, Croatia
| | - Vatroslav Šerić
- Department of Clinical Laboratory Diagnostics, University Hospital Centre Osijek, J. Huttlera 4, 31000, Osijek, Croatia
| | - Aleksandar Kibel
- Department of Physiology and Immunology, Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, J. Huttlera 4, 31000, Osijek, Croatia
- Department of Heart and Vascular Diseases, University Hospital Centre Osijek, J. Huttlera 4, 31000, Osijek, Croatia
| | - Nandu Goswami
- Physiology Division, Otto Loewi Research Center, Medical University of Graz, Auenbruggerplatz 2, 8036, Graz, Austria
| | - Bianca Brix
- Physiology Division, Otto Loewi Research Center, Medical University of Graz, Auenbruggerplatz 2, 8036, Graz, Austria
| | - Željko Debeljak
- Department of Clinical Laboratory Diagnostics, University Hospital Centre Osijek, J. Huttlera 4, 31000, Osijek, Croatia
- Department of Pharmacology, Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, J. Huttlera 4, 31000, Osijek, Croatia
| | - Rudolf Scitovski
- Department of Mathematics, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia
| | - Ines Drenjančević
- Department of Physiology and Immunology, Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, J. Huttlera 4, 31000, Osijek, Croatia.
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Mankoo A, Roy S, Davies A, Panerai RB, Robinson TG, Brassard P, Beishon LC, Minhas JS. The role of the autonomic nervous system in cerebral blood flow regulation in stroke: A review. Auton Neurosci 2023; 246:103082. [PMID: 36870192 DOI: 10.1016/j.autneu.2023.103082] [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: 12/24/2021] [Revised: 11/22/2022] [Accepted: 02/22/2023] [Indexed: 03/02/2023]
Abstract
Stroke is a pathophysiological condition which results in alterations in cerebral blood flow (CBF). The mechanism by which the brain maintains adequate CBF in presence of fluctuating cerebral perfusion pressure (CPP) is known as cerebral autoregulation (CA). Disturbances in CA may be influenced by a number of physiological pathways including the autonomic nervous system (ANS). The cerebrovascular system is innervated by adrenergic and cholinergic nerve fibers. The role of the ANS in regulating CBF is widely disputed owing to several factors including the complexity of the ANS and cerebrovascular interactions, limitations to measurements, variation in methods to assess the ANS in relation to CBF as well as experimental approaches that can or cannot provide insight into the sympathetic control of CBF. CA is known to be impaired in stroke however the number of studies investigating the mechanisms by which this occurs are limited. This literature review will focus on highlighting the assessment of the ANS and CBF via indices derived from the analyses of heart rate variability (HRV), and baroreflex sensitivity (BRS), and providing a summary of both clinical and animal model studies investigating the role of the ANS in influencing CA in stroke. Understanding the mechanisms by which the ANS influences CBF in stroke patients may provide the foundation for novel therapeutic approaches to improve functional outcomes in stroke patients.
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Affiliation(s)
- Alex Mankoo
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom
| | - Sankanika Roy
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom.
| | - Aaron Davies
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom
| | - Ronney B Panerai
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom; NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom
| | - Thompson G Robinson
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom; NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, QC, Canada; Research center of the Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, QC, Canada
| | - Lucy C Beishon
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom
| | - Jatinder S Minhas
- University of Leicester, Department of Cardiovascular Sciences, Leicester, United Kingdom; NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom
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5
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Wu S, Tyler LK, Henson RNA, Rowe JB, Cam-Can, Tsvetanov KA. Cerebral blood flow predicts multiple demand network activity and fluid intelligence across the adult lifespan. Neurobiol Aging 2023; 121:1-14. [PMID: 36306687 PMCID: PMC7613814 DOI: 10.1016/j.neurobiolaging.2022.09.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 10/14/2022]
Abstract
The preservation of cognitive function in old age is a public health priority. Cerebral hypoperfusion is a hallmark of dementia but its impact on maintaining cognitive ability across the lifespan is less clear. We investigated the relationship between baseline cerebral blood flow (CBF) and blood oxygenation level-dependent (BOLD) response during a fluid reasoning task in a population-based adult lifespan cohort. As age differences in CBF could lead to non-neuronal contributions to the BOLD signal, we introduced commonality analysis to neuroimaging to dissociate performance-related CBF effects from the physiological confounding effects of CBF on the BOLD response. Accounting for CBF, we confirmed that performance- and age-related differences in BOLD responses in the multiple-demand network were implicated in fluid reasoning. Age differences in CBF explained not only performance-related BOLD responses but also performance-independent BOLD responses. Our results suggest that CBF is important for maintaining cognitive function, while its non-neuronal contributions to BOLD signals reflect an age-related confound. Maintaining perfusion into old age may serve to support brain function and preserve cognitive performance.
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Affiliation(s)
- Shuyi Wu
- Centre for Speech, Language and the Brain, Department of Psychology, University of Cambridge, Cambridge, UK; Department of Management, School of Business, Hong Kong Baptist University, Hong Kong, China
| | - Lorraine K Tyler
- Centre for Speech, Language and the Brain, Department of Psychology, University of Cambridge, Cambridge, UK
| | - Richard N A Henson
- Medical Research Council Cognition and Brain Sciences Unit, Department of Psychiatry, Cambridge, UK
| | - James B Rowe
- Medical Research Council Cognition and Brain Sciences Unit, Department of Psychiatry, Cambridge, UK; Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Cam-Can
- Centre for Speech, Language and the Brain, Department of Psychology, University of Cambridge, Cambridge, UK; Medical Research Council Cognition and Brain Sciences Unit, Department of Psychiatry, Cambridge, UK
| | - Kamen A Tsvetanov
- Centre for Speech, Language and the Brain, Department of Psychology, University of Cambridge, Cambridge, UK; Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
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6
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Barranca C, Pereira TJ, Edgell H. Oral contraceptive use and menstrual cycle influence acute cerebrovascular response to standing. Auton Neurosci 2023; 244:103054. [PMID: 36516546 DOI: 10.1016/j.autneu.2022.103054] [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: 06/20/2022] [Revised: 10/25/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022]
Abstract
PURPOSE To determine if the menstrual cycle and oral contraceptives (OC) influence responses to acute orthostatic stress and if these factors are clinically relevant to the diagnosis of initial orthostatic hypotension (iOH). METHODS Young, healthy women were recruited, including OC users (n = 12) and non-users (NOC; n = 9). Women were tested during the low hormone (LH; placebo pills; days 2-5 natural cycle) and high hormone (HH; active dose; days 18-24 natural cycle) menstrual phases. Changes in mean arterial pressure, cardiac output, heart rate, the 30:15 heart rate ratio and cerebrovascular resistance indices within 30 s of standing were examined. RESULTS There were no effects of OC or menstrual cycle on hemodynamic responses during standing (all p>0.05). In the LH phase, OC users had a greater fall in mean middle cerebral artery blood velocity (MCAV) compared to NOC (p<0.05). However, this was reversed in the HH phase, where OC users had a reduced fall in mean MCAV (p<0.05). Interestingly, 8 women (OC and NOC) had drops in systolic/diastolic blood pressure meeting the criteria for iOH, and 7 of those 8 women displayed this drop in a single phase of the menstrual cycle. CONCLUSION Our results indicate that chronic versus acute OC use (i.e., long-term use observed via LH phase versus short-term use observed via HH phase) have opposing effects on cerebral blood velocity during standing. Further, our results highlight that multiple assessments across the cycle may be necessary to accurately diagnose iOH, as most women met the diagnostic criteria during a single menstrual phase.
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Affiliation(s)
- C Barranca
- School of Kinesiology and Health Sciences, York University, Toronto, ON M3J1P3, Canada
| | - T J Pereira
- School of Kinesiology and Health Sciences, York University, Toronto, ON M3J1P3, Canada
| | - H Edgell
- School of Kinesiology and Health Sciences, York University, Toronto, ON M3J1P3, Canada; Muscle Health Research Centre, York University, Toronto, ON, Canada.
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Abbariki F, Roy M, Labrecque L, Drapeau A, Imhoff S, Smirl JD, Brassard P. Influence of high-intensity interval training to exhaustion on the directional sensitivity of the cerebral pressure-flow relationship in young endurance-trained men. Physiol Rep 2022; 10:e15384. [PMID: 35822439 PMCID: PMC9277516 DOI: 10.14814/phy2.15384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023] Open
Abstract
We previously reported subtle dynamic cerebral autoregulation (dCA) alterations following 6 weeks of high-intensity interval training (HIIT) to exhaustion using transfer function analysis (TFA) on forced mean arterial pressure (MAP) oscillations in young endurance-trained men. However, accumulating evidence suggests the cerebrovasculature better buffers cerebral blood flow changes when MAP acutely increases compared to when MAP acutely decreases. Whether HIIT affects the directional sensitivity of the cerebral pressure-flow relationship in these athletes is unknown. In 18 endurance-trained men (age: 27 ± 6 years, VO2 max: 55.5 ± 4.7 ml·kg-1 ·min-1 ), we evaluated the impact of 6 weeks of HIIT to exhaustion on dCA directionality using induced MAP oscillations during 5-min 0.05 and 0.10 Hz repeated squat-stands. We calculated time-adjusted changes in middle cerebral artery mean blood velocity (MCAv) per change in MAP (ΔMCAvT /ΔMAPT ) for each squat transition. Then, we compared averaged ΔMCAvT /ΔMAPT during MAP increases and decreases. Before HIIT, ΔMCAvT /ΔMAPT was comparable between MAP increases and decreases during 0.05 Hz repeated squat-stands (p = 0.518). During 0.10 Hz repeated squat-stands, ΔMCAvT /ΔMAPT was lower during MAP increases versus decreases (0.87 ± 0.17 vs. 0.99 ± 0.23 cm·s-1 ·mmHg-1 , p = 0.030). Following HIIT, ΔMCAvT /ΔMAPT was superior during MAP increases over decreases during 0.05 Hz repeated squat-stands (0.97 ± 0.38 vs. 0.77 ± 0.35 cm·s-1 ·mmHg-1 , p = 0.002). During 0.10 Hz repeated squat-stands, dCA directional sensitivity disappeared (p = 0.359). These results suggest the potential for HIIT to influence the directional sensitivity of the cerebral pressure-flow relationship in young endurance-trained men.
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Affiliation(s)
- Faezeh Abbariki
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébec CityQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébec CityQuébecCanada
| | - Marc‐Antoine Roy
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébec CityQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébec CityQuébecCanada
| | - Lawrence Labrecque
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébec CityQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébec CityQuébecCanada
| | - Audrey Drapeau
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébec CityQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébec CityQuébecCanada
| | - Sarah Imhoff
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébec CityQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébec CityQuébecCanada
| | - Jonathan D. Smirl
- Cerebrovascular Concussion Laboratory, Faculty of KinesiologyUniversity of CalgaryCalgaryAlbertaCanada
- Sport Injury Prevention Research Centre, Faculty of KinesiologyUniversity of CalgaryCalgaryAlbertaCanada
- Human Performance Laboratory, Faculty of KinesiologyUniversity of CalgaryCalgaryAlbertaCanada
- Hotchkiss Brain InstituteUniversity of CalgaryCalgaryAlbertaCanada
- Integrated Concussion Research ProgramUniversity of CalgaryCalgaryAlbertaCanada
- Alberta Children's Hospital Research InstituteUniversity of CalgaryCalgaryAlbertaCanada
- Libin Cardiovascular Institute of AlbertaUniversity of CalgaryAlbertaCanada
- Concussion Research Laboratory, Faculty of Health and Exercise ScienceUniversity of British ColumbiaKelownaBritish ColumbiaCanada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of MedicineUniversité LavalQuébec CityQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de QuébecQuébec CityQuébecCanada
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8
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Korad S, Mündel T, Fan JL, Perry BG. Cerebral autoregulation across the menstrual cycle in eumenorrheic women. Physiol Rep 2022; 10:e15287. [PMID: 35524340 PMCID: PMC9076937 DOI: 10.14814/phy2.15287] [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: 04/07/2022] [Accepted: 04/11/2022] [Indexed: 12/20/2022] Open
Abstract
There is emerging evidence that ovarian hormones play a significant role in the lower stroke incidence observed in pre‐menopausal women compared with men. However, the role of ovarian hormones in cerebrovascular regulation remains to be elucidated. We examined the blood pressure‐cerebral blood flow relationship (cerebral autoregulation) across the menstrual cycle in eumenorrheic women (n = 12; mean ± SD: age, 31 ± 7 years). Participants completed sit‐to‐stand and Valsalva maneuvers (VM, mouth pressure of 40 mmHg for 15 s) during the early follicular (EF), late follicular (LF), and mid‐luteal (ML) menstrual cycle phases, confirmed by serum measurement of progesterone and 17β‐estradiol. Middle cerebral artery blood velocity (MCAv), arterial blood pressure and partial pressure of end‐tidal carbon dioxide were measured. Cerebral autoregulation was assessed by transfer function analysis during spontaneous blood pressure oscillations, rate of regulation (RoR) during sit‐to‐stand maneuvers, and Tieck’s autoregulatory index during VM phases II and IV (AI‐II and AI‐IV, respectively). Resting mean MCAv (MCAvmean), blood pressure, and cerebral autoregulation were unchanged across the menstrual cycle (all p > 0.12). RoR tended to be different (EF, 0.25 ± 0.06; LF; 0.19 ± 0.04; ML, 0.18 ± 0.12 sec−1; p = 0.07) and demonstrated a negative relationship with 17β‐estradiol (R2 = 0.26, p = 0.02). No changes in AI‐II (EF, 1.95 ± 1.20; LF, 1.67 ± 0.77 and ML, 1.20 ± 0.55) or AI‐IV (EF, 1.35 ± 0.21; LF, 1.27 ± 0.26 and ML, 1.20 ± 0.2) were observed (p = 0.25 and 0.37, respectively). Although, a significant interaction effect (p = 0.02) was observed for the VM MCAvmean response. These data indicate that the menstrual cycle has limited impact on cerebrovascular autoregulation, but individual differences should be considered.
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Affiliation(s)
- Stephanie Korad
- School of Health Sciences, Massey University, Wellington, New Zealand.,School of Sport, Exercise and Nutrition, Massey University, Palmerston North, New Zealand
| | - Toby Mündel
- School of Sport, Exercise and Nutrition, Massey University, Palmerston North, New Zealand
| | - Jui-Lin Fan
- Department of Physiology, Faculty of Medical and Health Sciences, Manaaki Manawa, The Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - Blake G Perry
- School of Health Sciences, Massey University, Wellington, New Zealand
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Fan JL, Brassard P, Rickards CA, Nogueira RC, Nasr N, McBryde FD, Fisher JP, Tzeng YC. Integrative cerebral blood flow regulation in ischemic stroke. J Cereb Blood Flow Metab 2022; 42:387-403. [PMID: 34259070 PMCID: PMC8985438 DOI: 10.1177/0271678x211032029] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Optimizing cerebral perfusion is key to rescuing salvageable ischemic brain tissue. Despite being an important determinant of cerebral perfusion, there are no effective guidelines for blood pressure (BP) management in acute stroke. The control of cerebral blood flow (CBF) involves a myriad of complex pathways which are largely unaccounted for in stroke management. Due to its unique anatomy and physiology, the cerebrovascular circulation is often treated as a stand-alone system rather than an integral component of the cardiovascular system. In order to optimize the strategies for BP management in acute ischemic stroke, a critical reappraisal of the mechanisms involved in CBF control is needed. In this review, we highlight the important role of collateral circulation and re-examine the pathophysiology of CBF control, namely the determinants of cerebral perfusion pressure gradient and resistance, in the context of stroke. Finally, we summarize the state of our knowledge regarding cardiovascular and cerebrovascular interaction and explore some potential avenues for future research in ischemic stroke.
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Affiliation(s)
- Jui-Lin Fan
- Manaaki Mānawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec City, Canada.,Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec City, Canada
| | - Caroline A Rickards
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Ricardo C Nogueira
- Neurology Department, School of Medicine, Hospital das Clinicas, University of São Paulo, São Paulo, Brazil.,Neurology Department, Hospital Nove de Julho, São Paulo, Brazil
| | - Nathalie Nasr
- Department of Neurology, Toulouse University Hospital, NSERM UMR 1297, Toulouse, France
| | - Fiona D McBryde
- Manaaki Mānawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - James P Fisher
- Manaaki Mānawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Yu-Chieh Tzeng
- Wellington Medical Technology Group, Department of Surgery and Anaesthesia, University of Otago, Wellington, New Zealand.,Department of Surgery & Anaesthesia, Centre for Translational Physiology, University of Otago, Wellington, New Zealand
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10
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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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11
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Llwyd O, Fan JL, Müller M. Effect of drug interventions on cerebral hemodynamics in ischemic stroke patients. J Cereb Blood Flow Metab 2022; 42:471-485. [PMID: 34738511 PMCID: PMC8985436 DOI: 10.1177/0271678x211058261] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The ischemic penumbra is sensitive to alterations in cerebral perfusion. A myriad of drugs are used in acute ischemic stroke (AIS) management, yet their impact on cerebral hemodynamics is poorly understood. As part of the Cerebral Autoregulation Network led INFOMATAS project (Identifying New Targets for Management and Therapy in Acute Stroke), this paper reviews some of the most common drugs a patient with AIS will come across and their potential influence on cerebral hemodynamics with a particular focus being on cerebral autoregulation (CA). We first discuss how compounds that promote clot lysis and prevent clot formation could potentially impact cerebral hemodynamics, before focusing on how the different classes of antihypertensive drugs can influence cerebral hemodynamics. We discuss the different properties of each drug and their potential impact on cerebral perfusion and CA. With emerging interest in CA status of AIS patients, either during or soon after treatment when timely reperfusion and salvageable tissue is at its most critical, the properties of these pharmacological agents may be relevant for modelling cerebral perfusion accuracy and for setting individualised treatment strategies.
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Affiliation(s)
- Osian Llwyd
- Department of Cardiovascular Sciences, Cerebral Haemodynamics in Ageing and Stroke Medicine Research Group, University of Leicester, Leicester, UK
| | - Jui-Lin Fan
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, Auckland, New Zealand
| | - Martin Müller
- Neurozentrum, Klinik für Neurologie und Neurorehabilitation, Luzerner Kantonsspital, Spitalstrasse, Luzern, Switzerland
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12
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Roy MA, Labrecque L, Perry BG, Korad S, Smirl JD, Brassard P. Directional sensitivity of the cerebral pressure-flow relationship in young healthy individuals trained in endurance and resistance exercise. Exp Physiol 2022; 107:299-311. [PMID: 35213765 DOI: 10.1113/ep090159] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 02/08/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does habitual exercise modality affect the directionality of the cerebral pressure-flow relationship? What is the main finding and its importance? These data suggest the hysteresis-like pattern of dynamic cerebral autoregulation appears present in long-term sedentary and endurance-trained individuals, but absent in resistance-trained individuals. This is the first study to expand knowledge on the directional sensitivity of the cerebral pressure-flow relationship to trained populations. ABSTRACT Evidence suggests the cerebrovasculature may be more efficient at dampening cerebral blood flow (CBF) variations when mean arterial pressure (MAP) transiently increases, compared to when it decreases. Despite divergent MAP and CBF responses to acute endurance and resistance training, the long-term impact of habitual exercise modality on the directionality of dynamic cerebral autoregulation (dCA) is currently unknown. Thirty-six young healthy participants [sedentary (n = 12), endurance-trained (n = 12) and resistance-trained (n = 12)] undertook a 5-min repeated squat-stand protocol at two forced MAP oscillation frequencies (0.05 Hz and 0.10 Hz). Middle cerebral artery mean blood velocity (MCAv) and MAP were continuously monitored. We calculated absolute (ΔMCAvT /ΔMAPT ) and relative (%MCAvT /%MAPT ) changes in MCAv and MAP with respect to the transition time intervals of both variables to compute a time-adjusted ratio in each MAP direction, averaged over the 5-min repeated squat-stand protocols. At 0.10 Hz repeated squat-stands, ΔMCAvT /ΔMAPT and %MCAvT /%MAPT were lower when MAP increased compared with when MAP decreased for sedentary (ΔMCAvT /ΔMAPT : p = 0.032; %MCAvT /%MAPT : p = 0.040) and endurance-trained individuals (ΔMCAvT /ΔMAPT : p = 0.012; %MCAvT /%MAPT : p = 0.007), but not in the resistance-trained (ΔMCAvT /ΔMAPT : p = 0.512; %MCAvT /%MAPT : p = 0.666). At 0.05 Hz repeated squat-stands, time-adjusted ratios were similar for all groups (all p>0.605). These findings suggest exercise training modality does influence the directionality of the cerebral pressure-flow relationship and support the presence of a hysteresis-like pattern during 0.10 Hz repeated squat-stands in sedentary and endurance-trained participants, but not in resistance-trained individuals. In future studies, assessment of elite endurance and resistance training habits may further elucidate modality-dependent discrepancies on directional dCA measurements. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Marc-Antoine Roy
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Blake G Perry
- School of Health Sciences, Massey University, Wellington, New Zealand.,School of Sport, Exercise and Nutrition, Massey University, Wellington, New Zealand
| | - Stephanie Korad
- School of Health Sciences, Massey University, Wellington, New Zealand.,School of Sport, Exercise and Nutrition, Massey University, Wellington, New Zealand
| | - Jonathan D Smirl
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.,Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada.,Concussion Research Laboratory, Faculty of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
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13
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Koep JL, Taylor CE, Coombes JS, Bond B, Ainslie PN, Bailey TG. Autonomic control of cerebral blood flow: fundamental comparisons between peripheral and cerebrovascular circulations in humans. J Physiol 2021; 600:15-39. [PMID: 34842285 DOI: 10.1113/jp281058] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/25/2021] [Indexed: 01/12/2023] Open
Abstract
Understanding the contribution of the autonomic nervous system to cerebral blood flow (CBF) control is challenging, and interpretations are unclear. The identification of calcium channels and adrenoreceptors within cerebral vessels has led to common misconceptions that the function of these receptors and actions mirror those of the peripheral vasculature. This review outlines the fundamental differences and complex actions of cerebral autonomic activation compared with the peripheral circulation. Anatomical differences, including the closed nature of the cerebrovasculature, and differential adrenoreceptor subtypes, density, distribution and sensitivity, provide evidence that measures on peripheral sympathetic nerve activity cannot be extrapolated to the cerebrovasculature. Cerebral sympathetic nerve activity seems to act opposingly to the peripheral circulation, mediated at least in part by changes in intracranial pressure and cerebral blood volume. Additionally, heterogeneity in cerebral adrenoreceptor distribution highlights region-specific autonomic regulation of CBF. Compensatory chemo- and autoregulatory responses throughout the cerebral circulation, and interactions with parasympathetic nerve activity are unique features to the cerebral circulation. This crosstalk between sympathetic and parasympathetic reflexes acts to ensure adequate perfusion of CBF to rising and falling perfusion pressures, optimizing delivery of oxygen and nutrients to the brain, while attempting to maintain blood volume and intracranial pressure. Herein, we highlight the distinct similarities and differences between autonomic control of cerebral and peripheral blood flow, and the regional specificity of sympathetic and parasympathetic regulation within the cerebrovasculature. Future research directions are outlined with the goal to further our understanding of autonomic control of CBF in humans.
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Affiliation(s)
- Jodie L Koep
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Chloe E Taylor
- School of Health Sciences, Western Sydney University, Sydney, Australia
| | - Jeff S Coombes
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Bert Bond
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Tom G Bailey
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,School of Nursing, Midwifery and Social Work, The University of Queensland, Brisbane, Queensland, Australia
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14
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Skow RJ, Labrecque L, Rosenberger JA, Brassard P, Steinback CD, Davenport MH. Prenatal exercise and cardiovascular health (PEACH) study: impact of acute and chronic exercise on cerebrovascular hemodynamics and dynamic cerebral autoregulation. J Appl Physiol (1985) 2021; 132:247-260. [PMID: 34818074 DOI: 10.1152/japplphysiol.00446.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We performed a randomised controlled trial measuring dynamic cerebral autoregulation (dCA) using a sit-to-stand maneuver before (SS1) and following (SS2) an acute exercise test at 16-20 weeks gestation (trimester 2; TM2) and then again at 34-37 weeks gestation (third trimester; TM3). Following the first assessment, women were randomised into exercise training or control (standard care) groups; women in the exercise training group were prescribed moderate intensity aerobic exercise for 25-40 minutes on 3-4 days per week for 14±1weeks. Resting seated mean blood velocity in the middle cerebral artery (MCAvmean) was lower in TM3 compared to TM2 but not impacted by exercise training intervention. dCA was not impacted by gestational age, or exercise training during SS1. During SS2, dCA was altered such that there were greater absolute and relative decreases in mean arterial blood pressure (MAP) and MCAvmean, but this was not impacted by the intervention. There was also no difference in the relationship between the decrease in MCAvmean compared to the decrease in MAP (%/%), or the onset of the regulatory response with respect to acute exercise, gestational age, or intervention; however, rate of regulation was faster in women in the exercise group following acute exercise (interaction effect, p=0.048). These data highlight the resilience of the cerebral circulation in that dCA was well maintained or improved in healthy pregnant women between TM2 and TM3. However, future work addressing the impact of acute and chronic exercise on dCA in women who are at risk for cardiovascular complications during pregnancy is needed.
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Affiliation(s)
- Rachel J Skow
- Program for Pregnancy and Postpartum Health, Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Lawrence Labrecque
- Department of Kinesiology and Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Canada
| | - Jade A Rosenberger
- Program for Pregnancy and Postpartum Health, Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Patrice Brassard
- Department of Kinesiology and Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Canada
| | - Craig D Steinback
- Program for Pregnancy and Postpartum Health, Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Margie H Davenport
- Program for Pregnancy and Postpartum Health, Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
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15
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Gelpi F, Bari V, Cairo B, De Maria B, Tonon D, Rossato G, Faes L, Porta A. Dynamic cerebrovascular autoregulation in patients prone to postural syncope: Comparison of techniques assessing the autoregulation index from spontaneous variability series. Auton Neurosci 2021; 237:102920. [PMID: 34808528 DOI: 10.1016/j.autneu.2021.102920] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 10/20/2021] [Accepted: 11/15/2021] [Indexed: 10/19/2022]
Abstract
Three approaches to the assessment of cerebrovascular autoregulation (CA) via the computation of the autoregulation index (ARI) from spontaneous variability of mean arterial pressure (MAP) and mean cerebral blood flow velocity (MCBFV) were applied: 1) a time domain method (TDM); 2) a nonparametric method (nonPM); 3) a parametric method (PM). Performances were tested over matched and surrogate unmatched pairs. Data were analyzed at supine resting (REST) and during the early phase of 60° head-up tilt (TILT) in 13 subjects with previous history of postural syncope (SYNC, age: 28 ± 9 yrs.; 5 males) and 13 control individuals (noSYNC, age: 27 ± 8 yrs.; 5 males). Analysis was completed by computing autonomic markers from heart period (HP) and systolic arterial pressure (SAP) variability series via spectral approach. HP and SAP spectral indexes suggested that noSYNC and SYNC groups exhibited different autonomic responses to TILT. ARI analysis indicated that: i) all methods have a sufficient statistical power to separate matched from unmatched pairs with the exception of nonPM applied to impulse response; ii) ARI estimates derived from different methods might be uncorrelated and, even when correlated, might exhibit a significant bias; iii) orthostatic stressor did not induce any evident ARI change in either noSYNC or SYNC individuals; iv) this conclusion held regardless of the method. Methods for the ARI estimation from spontaneous variability provide different ARIs but none indicate that noSYNC and SYNC subjects have different dynamic component of CA.
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Affiliation(s)
- Francesca Gelpi
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy; Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Vlasta Bari
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Beatrice Cairo
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | | | - Davide Tonon
- Department of Neurology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar, Verona, Italy
| | - Gianluca Rossato
- Department of Neurology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar, Verona, Italy
| | - Luca Faes
- Department of Engineering, University of Palermo, Palermo, Italy
| | - Alberto Porta
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy; Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.
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16
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Zhao Y, Liu P, Turner MP, Abdelkarim D, Lu H, Rypma B. The neural-vascular basis of age-related processing speed decline. Psychophysiology 2021; 58:e13845. [PMID: 34115388 DOI: 10.1111/psyp.13845] [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: 10/01/2020] [Revised: 04/14/2021] [Accepted: 04/19/2021] [Indexed: 12/12/2022]
Abstract
Most studies examining neurocognitive aging are based on the blood-oxygen level-dependent signal obtained during functional magnetic resonance imaging (fMRI). The physiological basis of this signal is neural-vascular coupling, the process by which neurons signal cerebrovasculature to dilate in response to an increase in active neural metabolism due to stimulation. These fMRI studies of aging rely on the hemodynamic equivalence assumption that this process is not disrupted by physiologic deterioration associated with aging. Studies of neural-vascular coupling challenge this assumption and show that neural-vascular coupling is closely related to cognition. In this review, we put forward a theory of processing speed decline in aging and how it is related to age-related neural-vascular coupling changes based on the results of studies elucidating the relationships between cognition, cerebrovascular dynamics, and aging.
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Affiliation(s)
- Yuguang Zhao
- School of Behavioral and Brain Sciences, Center for Brain Health, University of Texas at Dallas, Richardson, TX, USA
| | - Peiying Liu
- School of Medicine, Department of Radiology, Johns Hopkins University, Baltimore, MD, USA
| | - Monroe P Turner
- School of Behavioral and Brain Sciences, Center for Brain Health, University of Texas at Dallas, Richardson, TX, USA
| | - Dema Abdelkarim
- School of Behavioral and Brain Sciences, Center for Brain Health, University of Texas at Dallas, Richardson, TX, USA
| | - Hanzhang Lu
- School of Medicine, Department of Radiology, Johns Hopkins University, Baltimore, MD, USA
| | - Bart Rypma
- School of Behavioral and Brain Sciences, Center for Brain Health, University of Texas at Dallas, Richardson, TX, USA
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17
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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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18
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Zuj KA, Hedge ET, Milligan JD, Peterson SD, Hughson RL. Intermittent compression of the calf muscle as a countermeasure to protect blood pressure and brain blood flow in upright posture in older adults. Eur J Appl Physiol 2021; 121:839-848. [PMID: 33386985 DOI: 10.1007/s00421-020-04547-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 10/29/2020] [Indexed: 12/28/2022]
Abstract
PURPOSE Orthostatic hypotension, leading to cerebral hypoperfusion, can result in postural instability and falls in older adults. We determined the efficacy of a novel, intermittent pneumatic compression system, applying pressure around the lower legs, as a countermeasure against orthostatic stress in older adults. METHODS Data were collected from 13 adults (4 male) over 65 years of age. Non-invasive ultrasound measured middle cerebral artery blood velocity (MCAv) and finger photoplethysmography measured mean arterial blood pressure (MAP). Intermittent lower leg compression was applied in a peristaltic manner in the local diastolic phase of each cardiac cycle to optimize venous return during 1-min of seated rest and during a sit-to-stand transition to 1-min of quiet standing with compression initiated 15 s before transition. RESULTS During seated rest, compression resulted in a 4.5 ± 6.5 mmHg increase in MAP, and 2.3 ± 2.1 cm/s increase in MCAv (p < 0.05). MAP and MCAv increased during the 15 s of applied compression before the posture transition (2.3 ± 7.2 mmHg and 2.1 ± 4.0 cm/s, respectively, p < 0.05) with main effects for both variables confirming continued benefit during the transition and quiet stand periods. CONCLUSIONS Application of carefully timed, intermittent compression to the lower legs of older adults increased MAP and MCAv during seated rest and maintained an elevated MAP and MCAv during a transition to standing posture. Future research could assess the benefits of this technology for persons at risk for orthostatic hypotension on standing and while walking in an effort to reduce injurious, unexplained falls in older adults.
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Affiliation(s)
- K A Zuj
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada.,Schlegel-University of Waterloo Research Institute for Aging, 250 Laurelwood Dr., Waterloo, ON, N2J 0E2, Canada
| | - E T Hedge
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada.,Schlegel-University of Waterloo Research Institute for Aging, 250 Laurelwood Dr., Waterloo, ON, N2J 0E2, Canada
| | - J D Milligan
- Schlegel-University of Waterloo Research Institute for Aging, 250 Laurelwood Dr., Waterloo, ON, N2J 0E2, Canada.,Centre for Family Medicine, Kitchener, ON, Canada
| | - S D Peterson
- Department of Mechanical Engineering, University of Waterloo, Waterloo, ON, Canada
| | - R L Hughson
- Schlegel-University of Waterloo Research Institute for Aging, 250 Laurelwood Dr., Waterloo, ON, N2J 0E2, Canada.
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19
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Hemodynamics in acute stroke: Cerebral and cardiac complications. HANDBOOK OF CLINICAL NEUROLOGY 2021; 177:295-317. [PMID: 33632449 DOI: 10.1016/b978-0-12-819814-8.00015-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Hemodynamics is the study of blood flow, where parameters have been defined to quantify blood flow and the relationship with systemic circulatory changes. Understanding these perfusion parameters, the relationship between different blood flow variables and the implications for ischemic injury are outlined in the ensuing discussion. This chapter focuses on the hemodynamic changes that occur in ischemic stroke, and their contribution to ischemic stroke pathophysiology. We discuss the interaction between cardiovascular response and hemodynamic changes in stroke. Studying hemodynamic changes has a key role in stroke prevention, therapeutic implications and prognostic importance in acute ischemic stroke: preexisting hemodynamic and autoregulatory impairments predict the occurrence of stroke. Hemodynamic failure predisposes to the formation of thromboemboli and accelerates infarction due to impairing compensatory mechanisms. In ischemic stroke involving occlusion of a large vessel, persistent collateral circulation leads to preservation of ischemic penumbra and therefore justifying endovascular thrombectomy. Following thrombectomy, impaired autoregulation may lead to reperfusion injury and hemorrhage.
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20
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Tsukamoto H, Ishibashi A, Marley CJ, Shinohara Y, Ando S, Bailey DM, Hashimoto T, Ogoh S. Plasma brain-derived neurotrophic factor and dynamic cerebral autoregulation in acute response to glycemic control following breakfast in young men. Am J Physiol Regul Integr Comp Physiol 2021; 320:R69-R79. [PMID: 33112655 DOI: 10.1152/ajpregu.00059.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 10/20/2020] [Accepted: 10/20/2020] [Indexed: 11/22/2022]
Abstract
We examined the acute impact of both low- and high-glycemic index (GI) breakfasts on plasma brain-derived neurotrophic factor (BDNF) and dynamic cerebral autoregulation (dCA) compared with breakfast omission. Ten healthy men (age 24 ± 1 yr) performed three trials in a randomized crossover order; omission and Low-GI (GI = 40) and High-GI (GI = 71) breakfast conditions. Middle cerebral artery velocity (transcranial Doppler ultrasonography) and arterial pressure (finger photoplethysmography) were continuously measured for 5 min before and 120 min following breakfast consumption to determine dCA using transfer function analysis. After these measurements of dCA, venous blood samples for the assessment of plasma BDNF were obtained. Moreover, blood glucose was measured before breakfast and every 30 min thereafter. The area under the curve of 2 h postprandial blood glucose in the High-GI trial was higher than the Low-GI trial (P < 0.01). The GI of the breakfast did not affect BDNF. In addition, both very-low (VLF) and low-frequency (LF) transfer function phase or gains were not changed during the omission trial. In contrast, LF gain (High-GI P < 0.05) and normalized gain (Low-GI P < 0.05) were decreased by both GI trials, while a decrease in VLF phase was observed in only the High-GI trial (P < 0.05). These findings indicate that breakfast consumption augmented dCA in the LF range but High-GI breakfast attenuated cerebral blood flow regulation against slow change (i.e., the VLF range) in arterial pressure. Thus we propose that breakfast and glycemic control may be an important strategy to optimize cerebrovascular health.
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Affiliation(s)
- Hayato Tsukamoto
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, United Kingdom
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Aya Ishibashi
- Japan Institute of Sports Science, Tokyo, Japan
- Department of Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Christopher J Marley
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, United Kingdom
| | - Yasushi Shinohara
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Soichi Ando
- Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, United Kingdom
| | - Takeshi Hashimoto
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Shigehiko Ogoh
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, United Kingdom
- Department of Biomedical Engineering, Toyo University, Saitama, Japan
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21
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Robertson AD, Papadhima I, Edgell H. Sex differences in the autonomic and cerebrovascular responses to upright tilt. Auton Neurosci 2020; 229:102742. [PMID: 33197693 DOI: 10.1016/j.autneu.2020.102742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 01/11/2023]
Abstract
Sex differences in the regulation of autonomic and cerebrovascular responses to orthostatic stress remain unclear. The objectives of this study were to concurrently investigate autonomic control and cerebrovascular resistance indices, including critical closing pressure (CrCP) and resistance area product (RAP), during upright tilt in men and women. In 13 women and 14 men (18-29 years), ECG, non-invasive blood pressure, middle cerebral artery blood velocity, and end-tidal CO2 (ETCO2) were continuously measured during supine rest and 70° tilt. Heart rate variability (HRV), cardiovagal baroreflex sensitivity (cBRS), and transfer function parameters of dynamic cerebral autoregulation were calculated. Compared to supine, upright tilt increased the low frequency-to-high frequency ratio of HRV in men only (P = 0.044), and decreased cBRS more in women (P = 0.001). Cerebrovascular resistance index (CVRi) increased during tilt only in men (sex-by-time interaction: P = 0.004). RAP was lower in women throughout tilt (main effect of sex: P = 0.022). CrCP decreased during tilt in both sexes (main effect of time: P < 0.001). Normalizing to ETCO2 did not alter the effect of tilt on cerebrovascular resistance. Men displayed a greater increase of sympathetic indices and CVRi during tilt while women had greater parasympathetic withdrawal. We hypothesize that increased sympathetic activity in men may drive sex differences in the cerebrovascular response to upright posture.
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Affiliation(s)
- Andrew D Robertson
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada; Schlegel-UW Research Institute for Aging, University of Waterloo, Waterloo, Ontario, Canada
| | - Ismina Papadhima
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada
| | - Heather Edgell
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; Muscle Health Research Centre, York University, Toronto, Ontario, Canada.
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22
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Comparison of Pressure Reactivity Index and Mean Velocity Index to Evaluate Cerebrovascular Reactivity During Induced Arterial Blood Pressure Variations in Severe Brain Injury. Neurocrit Care 2020; 34:974-982. [PMID: 33006033 DOI: 10.1007/s12028-020-01092-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 08/28/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVES To compare the assessment of cerebral autoregulation by cerebrovascular reactivity indices based on intracranial pressure (Pressure Reactivity Index, PRx) and on transcranial Doppler (Mean Velocity Index, Mx) during controlled variations of arterial blood pressure in severe brain injury. Primary outcome was the agreement between both cerebrovascular reactivity indices measured by the Bland-and-Altman method. Secondary outcomes were the association of cerebrovascular reactivity indices with arterial blood pressure variation, and the comparison of optimal cerebral perfusion pressures determined by both indices. METHODS All consecutive comatose (Glasgow Coma Scale < 8) patients from the surgical intensive care unit of Bicetre Hospital who had an acute brain injury on computerized tomography and needed vasopressor support were prospectively included. Step-by-step arterial pressure variations using vasopressors were performed to compare PRx and Mx and to calculate optimal cerebral perfusion pressure (CPPopt). MEASUREMENTS AND MAIN RESULTS 15 patients were included. Mean difference between both indices measured by Bland-and-Altman plot was - 0.07 (IC 95% [- 1.02 to 0.87]). Mx was significantly associated with arterial pressure variation (one-way ANOVA test, p = 0.007), whereas PRx was not (p = 0.44). Optimal cerebral perfusion pressure calculated with PRx and Mx was respectively 11 and 15mmHg higher than the mean perfusion pressure prescribed. Optimal cerebral perfusion pressure calculation was possible in all cases. CONCLUSIONS Cerebral vasoreactivity indices calculated with intracranial pressure or transcranial Doppler show only moderate agreement. Both indices nonetheless suggest substantially higher optimal cerebral perfusion pressure than those currently provided by international guidelines.
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23
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Washio T, Watanabe H, Ogoh S. Dynamic cerebral autoregulation in anterior and posterior cerebral circulation during cold pressor test. J Physiol Sci 2020; 70:1. [PMID: 32039699 PMCID: PMC6987085 DOI: 10.1186/s12576-020-00732-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 01/22/2020] [Indexed: 12/26/2022]
Abstract
We hypothesized that cerebral blood flow (CBF) regulation in the posterior circulation differs from that of the anterior circulation during a cold pressor test (CPT) and is accompanied by elevations in arterial blood pressure (ABP) and sympathetic nervous activity (SNA). To test this, dynamic cerebral autoregulation (dCA) in the middle and posterior cerebral arteries (MCA and PCA) were measured at three different conditions: control, early phase of the CPT, and the late phase of the CPT. The dCA was examined using a thigh cuff occlusion and release technique. The MCA and PCA blood velocities were unchanged at CPT compared with the control conditions despite an elevation in the ABP. The dCA in both the MCA and PCA remained unaltered at CPT. These findings suggest that CPT-induced elevations in the ABP and SNA did not cause changes in the CBF regulation in the posterior circulation compared with the anterior circulation.
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Affiliation(s)
- Takuro Washio
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe-shi, Saitama, 350-8585, Japan.,Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Hironori Watanabe
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe-shi, Saitama, 350-8585, Japan
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe-shi, Saitama, 350-8585, Japan.
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24
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Acute hypotension attenuates brachial flow-mediated dilation in young healthy men. Eur J Appl Physiol 2019; 120:161-169. [PMID: 31701274 DOI: 10.1007/s00421-019-04260-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 11/01/2019] [Indexed: 12/11/2022]
Abstract
PURPOSE This study aimed to test our hypothesis that acute hypotension attenuates brachial flow-mediated dilation (FMD) as an index of endothelial function in healthy humans. METHODS Twelve healthy men (21.8 ± 1.6 years, body mass index; 22.2 ± 1.6 kg/m2) participated in this study. Brachial FMD was measured in three trials: standardized FMD protocol (control trial), abrupt decrease in blood pressure (BP) via thigh cuff inflation-deflation (hypotension trial) and decrease in shear rate (SR) via a shortened forearm occlusion time (SR reduction trial). Brachial diameter and blood velocity were measured using Duplex ultrasound. RESULTS Mean arterial pressure during reactive hyperaemia showed a marked decrease in the hypotension trial (- 23.7 ± 6.0 mmHg), but not in the control and SR reduction trials. SR area under the curve was attenuated in the SR reduction trial (P < 0.001), but not in the control and hypotension trials (P = 0.316). Consequently, FMD was attenuated in the hypotension and SR reduction trials compared with that in the control trial (P = 0.003 and P = 0.043, respectively), and was attenuated to a greater extent in the hypotension trial compared with the SR reduction trial (P = 0.006; control, 6.9 ± 3.5%; hypotension, 3.5 ± 1.7%; SR reduction, 5.0 ± 2.2%). After adjusting FMD using SR, FMD remained attenuated in the hypotension trial (P = 0.014), but not in the SR reduction trial. CONCLUSION Our findings indicate that arterial pressure as well as sympathetic nervous system activation could be an important determinant of FMD. Blunted FMD of peripheral arteries may be a rational response to restore BP and/or prevent further reduction of BP following acute hypotension in healthy humans.
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25
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Ogoh S, Tarumi T. Cerebral blood flow regulation and cognitive function: a role of arterial baroreflex function. J Physiol Sci 2019; 69:813-823. [PMID: 31444691 PMCID: PMC10717347 DOI: 10.1007/s12576-019-00704-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 08/13/2019] [Indexed: 10/26/2022]
Abstract
A strict adequate perfusion pressure via arterial baroreflex for the delivery of oxygen to the tissues of the body is well established; however, the importance of baroreflex for cerebral blood flow (CBF) is unclear. On the other hand, there is convincing evidence for arterial baroreflex function playing an important role in maintaining brain homeostasis, e.g., cerebral metabolism, cerebral hemodynamics, and cognitive function. For example, mild cognitive impairment attenuates the sensitivity of baroreflex, and Alzheimer's disease further decreases it. These clinical findings suggest that CBF and cerebral function are affected by systemic blood pressure regulation via the arterial baroreflex. However, dysfunction of arterial baroreflex is likely to affect CBF regulation as well as the underlying neuronal function, but identifying how this is achieved is arduous since neurological diseases affect systemic as well as cerebral circulation independently. Recent insights into the influence of blood pressure regulation via the arterial baroreflex on cerebral function and blood flow regulation may help elucidate this important question. This review summarizes some update findings regarding direct (autonomic regulation) and indirect (systemic blood pressure regulation) contributions of the arterial baroreflex to the maintenance of cerebral vasculature regulation.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama, 350-8585, Japan.
| | - Takashi Tarumi
- Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
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26
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Ogoh S. Interaction between the respiratory system and cerebral blood flow regulation. J Appl Physiol (1985) 2019; 127:1197-1205. [DOI: 10.1152/japplphysiol.00057.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This review summarizes the interaction between the regulatory system of respiration and cerebral vasculature. Some clinical reports provide evidence for the association between these two physiological regulatory systems. Physiologically, arterial carbon dioxide concentration is mainly regulated by two feedback control systems: respiration and cerebral blood flow. In other words, both of these systems are sensitive to the same mediator, i.e., carbon dioxide, at a set point. In addition, respiratory dysfunction alters various physiological factors that affect the cerebral vasculature. Therefore, it is physiologically plausible that these systems are closely linked. The regulation of arterial carbon dioxide concentration affected by respiration and cerebral blood flow may be a key factor for a rise in the risk of brain disease in the patients with respiratory dysfunction. For example, the management of respiratory disease (e.g., patients with chronic obstructive pulmonary disease) and the use of prophylactic therapy are essential to reduce the risk of stroke.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
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27
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Immink RV, Sperna Weiland NH, van den Dool REC, van der Ster BJP, Hollmann MW. Cerebral autoregulation: with age comes wisdom. Br J Anaesth 2019; 123:e466-e468. [PMID: 31280889 DOI: 10.1016/j.bja.2019.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/06/2019] [Accepted: 06/06/2019] [Indexed: 11/24/2022] Open
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28
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Purkayastha S, Williams B, Murphy M, Lyng S, Sabo T, Bell KR. Reduced heart rate variability and lower cerebral blood flow associated with poor cognition during recovery following concussion. Auton Neurosci 2019; 220:102548. [DOI: 10.1016/j.autneu.2019.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 03/12/2019] [Accepted: 04/27/2019] [Indexed: 11/24/2022]
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29
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Stotesbury H, Kawadler JM, Hales PW, Saunders DE, Clark CA, Kirkham FJ. Vascular Instability and Neurological Morbidity in Sickle Cell Disease: An Integrative Framework. Front Neurol 2019; 10:871. [PMID: 31474929 PMCID: PMC6705232 DOI: 10.3389/fneur.2019.00871] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/26/2019] [Indexed: 12/20/2022] Open
Abstract
It is well-established that patients with sickle cell disease (SCD) are at substantial risk of neurological complications, including overt and silent stroke, microstructural injury, and cognitive difficulties. Yet the underlying mechanisms remain poorly understood, partly because findings have largely been considered in isolation. Here, we review mechanistic pathways for which there is accumulating evidence and propose an integrative systems-biology framework for understanding neurological risk. Drawing upon work from other vascular beds in SCD, as well as the wider stroke literature, we propose that macro-circulatory hyper-perfusion, regions of relative micro-circulatory hypo-perfusion, and an exhaustion of cerebral reserve mechanisms, together lead to a state of cerebral vascular instability. We suggest that in this state, tissue oxygen supply is fragile and easily perturbed by changes in clinical condition, with the potential for stroke and/or microstructural injury if metabolic demand exceeds tissue oxygenation. This framework brings together recent developments in the field, highlights outstanding questions, and offers a first step toward a linking pathophysiological explanation of neurological risk that may help inform future screening and treatment strategies.
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Affiliation(s)
- Hanne Stotesbury
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom
| | - Jamie M Kawadler
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom
| | - Patrick W Hales
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom
| | - Dawn E Saunders
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom.,Department of Radiology, Great Ormond Hospital, London, United Kingdom
| | - Christopher A Clark
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom
| | - Fenella J Kirkham
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom.,Clinical and Experimental Sciences, University of Southampton, Southampton, United Kingdom.,Department of Child Health, University Hospital Southampton, Southampton, United Kingdom.,Department of Paediatric Neurology, Kings College Hospital NHS Foundation Trust, London, United Kingdom
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30
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Moir ME, Klassen SA, Al-Khazraji BK, Woehrle E, Smith SO, Matushewski BJ, Kozić D, Dujić Ž, Barak OF, Shoemaker JK. Impaired dynamic cerebral autoregulation in trained breath-hold divers. J Appl Physiol (1985) 2019; 126:1694-1700. [PMID: 31070952 DOI: 10.1152/japplphysiol.00210.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Breath-hold divers (BHD) experience repeated bouts of severe hypoxia and hypercapnia with large increases in blood pressure. However, the impact of long-term breath-hold diving on cerebrovascular control remains poorly understood. The ability of cerebral blood vessels to respond rapidly to changes in blood pressure represents the property of dynamic autoregulation. The current investigation tested the hypothesis that breath-hold diving impairs dynamic autoregulation to a transient hypotensive stimulus. Seventeen BHD (3 women, 11 ± 9 yr of diving) and 15 healthy controls (2 women) completed two or three repeated sit-to-stand trials during spontaneous breathing and poikilocapnic conditions. Heart rate (HR), finger arterial blood pressure (BP), and cerebral blood flow velocity (BFV) from the right middle cerebral artery were measured continuously with three-lead electrocardiography, finger photoplethysmography, and transcranial Doppler ultrasonography, respectively. End-tidal carbon dioxide partial pressure was measured with a gas analyzer. Offline, an index of cerebrovascular resistance (CVRi) was calculated as the quotient of mean BP and BFV. The rate of the drop in CVRi relative to the change in BP provided the rate of regulation [RoR; (∆CVRi/∆T)/∆BP]. The BHD demonstrated slower RoR than controls (P ≤ 0.001, d = 1.4). Underlying the reduced RoR in BHD was a longer time to reach nadir CVRi compared with controls (P = 0.004, d = 1.1). In concert with the longer CVRi response, the time to reach peak BFV following standing was longer in BHD than controls (P = 0.01, d = 0.9). The data suggest impaired dynamic autoregulatory mechanisms to hypotension in BHD. NEW & NOTEWORTHY Impairments in dynamic cerebral autoregulation to hypotension are associated with breath-hold diving. Although weakened autoregulation was observed acutely in this group during apneic stress, we are the first to report on chronic adaptations in cerebral autoregulation. Impaired vasomotor responses underlie the reduced rate of regulation, wherein breath-hold divers demonstrate a prolonged dilatory response to transient hypotension. The slower cerebral vasodilation produces a longer perturbation in cerebral blood flow velocity, increasing the risk of cerebral ischemia.
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Affiliation(s)
- M Erin Moir
- School of Kinesiology, University of Western Ontario , London, Ontario , Canada
| | - Stephen A Klassen
- School of Kinesiology, University of Western Ontario , London, Ontario , Canada
| | - Baraa K Al-Khazraji
- School of Kinesiology, University of Western Ontario , London, Ontario , Canada
| | - Emilie Woehrle
- School of Kinesiology, University of Western Ontario , London, Ontario , Canada
| | - Sydney O Smith
- School of Kinesiology, University of Western Ontario , London, Ontario , Canada
| | - Brad J Matushewski
- School of Kinesiology, University of Western Ontario , London, Ontario , Canada
| | - Duško Kozić
- Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia
| | - Željko Dujić
- Department of Physiology, University of Split School of Medicine , Split , Croatia
| | - Otto F Barak
- Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Faculty of Sports and Physical Education, University of Novi Sad, Novi Sad, Serbia
| | - 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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31
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Ackland GL, Brudney CS, Cecconi M, Ince C, Irwin MG, Lacey J, Pinsky MR, Grocott MPW, Mythen MG, Edwards MR, Miller TE, Miller TE, Mythen MG, Grocott MPW, Edwards MR, Ackland GL, Brudney CS, Cecconi M, Ince C, Irwin MG, Lacey J, Pinsky MR, Sanders R, Hughes F, Bader A, Thompson A, Hoeft A, Williams D, Shaw AD, Sessler DI, Aronson S, Berry C, Gan TJ, Kellum J, Plumb J, Bloomstone J, McEvoy MD, Thacker JK, Gupta R, Koepke E, Feldheiser A, Levett D, Michard F, Hamilton M. Perioperative Quality Initiative consensus statement on the physiology of arterial blood pressure control in perioperative medicine. Br J Anaesth 2019; 122:542-551. [DOI: 10.1016/j.bja.2019.01.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 12/10/2018] [Accepted: 01/02/2019] [Indexed: 01/19/2023] Open
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32
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Saleem S, Sarafis ZK, Lee AHX, Squair JW, Barak OF, Sober-Williams E, Suraj R, Coombs GB, Mijacika T, West CR, Krassioukov AV, Ainslie PN, Dujic Z, Tzeng YC, Phillips AA. Spinal Cord Disruption Is Associated with a Loss of Cushing-Like Blood Pressure Interactions. J Neurotrauma 2019; 36:1487-1490. [PMID: 30458117 DOI: 10.1089/neu.2018.5931] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The capacity of the cerebrovasculature to buffer changes in blood pressure (BP) likely plays an important role in the prevention of stroke, which is three- to fourfold more common after spinal cord injury (SCI). Although the directional relationship between BP and cerebral blood flow (CBF) has traditionally been thought to travel solely from BP to CBF, a Cushing-like mechanism functioning in the inverse direction, in which changes in CBF influence BP, has recently been revealed using Granger causality analysis. Although both CBF buffering of BP and the Cushing-like mechanism are influenced by the sympathetic nervous system, we do not understand the impact of disruption of descending sympathetic pathways within the spinal cord, caused by cervical SCI on these regulatory systems. We hypothesized that people with cervical SCI would have greater BP to CBF transmission, as well as a reduced Cushing-like mechanism. The directional relationships between mean arterial BP (MAP; Finometer® PRO) and middle cerebral artery blood velocity (MCAv; transcranial Doppler) were assessed at rest in 14 cervical SCI subjects and 16 uninjured individuals using Granger causality analysis, while also accounting for end-tidal CO2 tension. Those with SCI exhibited 66% increased forward MAP→MCAv information transmission as compared with the uninjured group (p = 0.0003), indicating reduced cerebrovascular buffering of BP, and did not have a predominant backward Cushing-like MCAv→MAP phenotype. These results indicate that both forward and backward communication between BP and CBF are influenced by SCI, which may be associated with impaired cerebrovascular BP buffering after SCI as well as widespread BP instability.
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Affiliation(s)
- Saqib Saleem
- 1 Department of Electrical & Computer Engineering, COMSATS University Islamabad, Sahiwal, Pakistan
| | - Zoe K Sarafis
- 2 International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Amanda H X Lee
- 2 International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,3 Experimental Medicine Program, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jordan W Squair
- 2 International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,3 Experimental Medicine Program, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,5 MD/PhD Training Program, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,4 Departments of Physiology and Pharmacology, Cardiac Sciences & Clinical Neurosciences, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Foothills Calgary, Alberta, Canada
| | - Otto F Barak
- 6 Faculty of Medicine, University of Novi Sad, Novi Sad, Republic of Serbia.,7 Faculty of Sport and Physical Education, University of Novi Sad, Novi Sad, Republic of Serbia
| | - Elin Sober-Williams
- 4 Departments of Physiology and Pharmacology, Cardiac Sciences & Clinical Neurosciences, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Foothills Calgary, Alberta, Canada
| | - Rejitha Suraj
- 4 Departments of Physiology and Pharmacology, Cardiac Sciences & Clinical Neurosciences, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Foothills Calgary, Alberta, Canada
| | - Geoff B Coombs
- 8 Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Tanja Mijacika
- 9 Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Christopher R West
- 2 International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Andrei V Krassioukov
- 2 International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Philip N Ainslie
- 8 Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Zeljko Dujic
- 9 Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Yu-Chieh Tzeng
- 10 Wellington Medical Technology Group, Department of Surgery and Anaesthesia, University of Otago, Wellington, New Zealand
| | - Aaron A Phillips
- 4 Departments of Physiology and Pharmacology, Cardiac Sciences & Clinical Neurosciences, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Foothills Calgary, Alberta, Canada
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TSUKAMOTO HAYATO, HASHIMOTO TAKESHI, OLESEN NIELSD, PETERSEN LONNIEG, SØRENSEN HENRIK, NIELSEN HENNINGB, SECHER NIELSH, OGOH SHIGEHIKO. Dynamic Cerebral Autoregulation Is Maintained during High-Intensity Interval Exercise. Med Sci Sports Exerc 2019; 51:372-378. [DOI: 10.1249/mss.0000000000001792] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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34
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Labrecque L, Rahimaly K, Imhoff S, Paquette M, Le Blanc O, Malenfant S, Drapeau A, Smirl JD, Bailey DM, Brassard P. Dynamic cerebral autoregulation is attenuated in young fit women. Physiol Rep 2019; 7:e13984. [PMID: 30652420 PMCID: PMC6335382 DOI: 10.14814/phy2.13984] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 12/28/2018] [Indexed: 02/07/2023] Open
Abstract
Young women exhibit higher prevalence of orthostatic hypotension with presyncopal symptoms compared to men. These symptoms could be influenced by an attenuated ability of the cerebrovasculature to respond to rapid blood pressure (BP) changes [dynamic cerebral autoregulation (dCA)]. The influence of sex on dCA remains unclear. dCA in 11 fit women (25 ± 2 years) and 11 age-matched men (24 ± 1 years) was compared using a multimodal approach including a sit-to-stand (STS) and forced BP oscillations (repeated squat-stand performed at 0.05 and 0.10 Hz). Prevalence of initial orthostatic hypotension (IOH; decrease in systolic ≥ 40 mmHg and/or diastolic BP ≥ 20 mmHg) during the first 15 sec of STS was determined as a functional outcome. In women, the decrease in mean middle cerebral artery blood velocity (MCAvmean ) following the STS was greater (-20 ± 8 vs. -11 ± 7 cm sec-1 ; P = 0.018) and the onset of the regulatory change (time lapse between the beginning of the STS and the increase in the conductance index (MCAvmean /mean arterial pressure) was delayed (P = 0.007). Transfer function analysis gain during 0.05 Hz squat-stand was ~48% higher in women (6.4 ± 1.3 vs. 3.8 ± 2.3 cm sec-1 mmHg-1 ; P = 0.017). Prevalence of IOH was comparable between groups (women: 4/9 vs. men: 5/9, P = 0.637). These results indicate the cerebrovasculature of fit women has an attenuated ability to react to rapid changes in BP in the face of preserved orthostasis, which could be related to higher resting cerebral blood flow allowing women to better face transient hypotension.
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Affiliation(s)
- Lawrence Labrecque
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Kevan Rahimaly
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Sarah Imhoff
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Myriam Paquette
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Olivier Le Blanc
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Simon Malenfant
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Audrey Drapeau
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Jonathan D. Smirl
- Concussion Research LaboratoryHealth and Exercise SciencesUniversity of British Columbia OkanaganBritish ColumbiaCanada
| | - Damian M. Bailey
- Neurovascular Research LaboratoryFaculty of Life Sciences and EducationUniversity of South WalesSouth WalesUnited Kingdom
| | - Patrice Brassard
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
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Teixeira SC, Madureira JB, Azevedo EI, Castro PM. Ageing affects the balance between central and peripheral mechanisms of cerebrovascular regulation with increasing influence of systolic blood pressure levels. Eur J Appl Physiol 2018; 119:519-529. [PMID: 30467594 DOI: 10.1007/s00421-018-4036-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 11/15/2018] [Indexed: 01/02/2023]
Abstract
BACKGROUND Arterial baroreflex (BR) and cerebral autoregulation (CA) are two major regulatory mechanisms that maintain constant cerebral perfusion. Little is known about the interplay between these mechanisms, particularly when considering the effects of ageing or sex. PURPOSE We studied the relationship between dynamic CA and BR sensitivity (BRS) in healthy subjects by sex and in different age strata. METHODS 95 healthy adults (52% female), 20-80 years-old, were recruited. Arterial blood pressure (Finometer), 3-lead electrocardiogram and cerebral blood flow velocity in middle cerebral arteries (transcranial Doppler) were monitored. We assessed CA by transfer function analysis and BRS in frequency and time domain. RESULTS With increasing age, BRS diminished (ANCOVA R2 = 0.281, p < 0.001) but CA parameters did not change significantly (p > 0.05). Overall, there was an inverse relationship between the efficacy of BRS and CA low-frequency gain [multivariate linear regression β = 0.41 (0.31; 0.61), p < 0.001]. However, this association suffers changes with ageing: in older subjects BRS and CA were not correlated [β = 0.10 (- 0.41; 0.62), p = 0.369]. Instead, decreasing systolic blood pressure correlated with less efficient CA [lower CA low-frequency gain β = - 0.02 (- 0.03; - 0.02), p = 0.003]. Sex did not affect BRS and CA relationship. CONCLUSIONS Cerebral blood supply is governed by a tuned balance between BR and CA which is lost with age as BRS decreases dramatically. Low systolic blood pressure values might be harmful to older subjects as they might reduce the ability to keep cerebral blood flow tightly controlled.
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Affiliation(s)
- Sofia Cunha Teixeira
- Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal.
| | - João Brandão Madureira
- Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal
| | - Elsa Irene Azevedo
- Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal.,Cardiovascular Research and Development Centre, Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Neurology, São João Hospital Centre, Porto, Portugal
| | - Pedro Miguel Castro
- Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal.,Cardiovascular Research and Development Centre, Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Neurology, São João Hospital Centre, Porto, Portugal
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36
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Labrecque L, Rahimaly K, Imhoff S, Paquette M, Le Blanc O, Malenfant S, Lucas SJE, Bailey DM, Smirl JD, Brassard P. Diminished dynamic cerebral autoregulatory capacity with forced oscillations in mean arterial pressure with elevated cardiorespiratory fitness. Physiol Rep 2018; 5:5/21/e13486. [PMID: 29122957 PMCID: PMC5688778 DOI: 10.14814/phy2.13486] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 10/07/2017] [Indexed: 12/12/2022] Open
Abstract
The effect that cardiorespiratory fitness has on the dynamic cerebral autoregulatory capacity during changes in mean arterial pressure (MAP) remains equivocal. Using a multiple‐metrics approach, challenging MAP across the spectrum of physiological extremes (i.e., spontaneous through forced MAP oscillations), we characterized dynamic cerebral autoregulatory capacity in 19 male endurance athletes and eight controls via three methods: (1) onset of regulation (i.e., time delay before an increase in middle cerebral artery (MCA) conductance [MCA blood velocity (MCAv)/MAP] and rate of regulation, after transient hypotension induced by sit‐to‐stand, and transfer function analysis (TFA) of MAP and MCAv responses during (2) spontaneous and (3) forced oscillations (5‐min of squat‐stand maneuvers performed at 0.05 and 0.10 Hz). Reductions in MAP and mean MCAv (MCAVmean) during initial orthostatic stress (0‐30 sec after sit‐to‐stand) and the prevalence of orthostatic hypotension were also determined. Onset of regulation was delayed after sit‐to‐stand in athletes (3.1 ± 1.7 vs. 1.5 ± 1.0 sec; P = 0.03), but rate of regulation was not different between groups (0.24 ± 0.05 vs. 0.21 ± 0.09 sec−1; P = 0.82). While both groups had comparable TFA metrics during spontaneous oscillations, athletes had higher TFA gain during 0.10 Hz squat‐stand versus recreational controls (P = 0.01). Reductions in MAP (P = 0.15) and MCAVmean (P = 0.11) during orthostatic stress and the prevalence of initial orthostatic hypotension (P = 0.65) were comparable between groups. These results indicate an intact ability of the cerebral vasculature to react to spontaneous oscillations but an attenuated capability to counter rapid and large changes in MAP in individuals with elevated cardiorespiratory fitness.
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Affiliation(s)
- Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Kevan Rahimaly
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Sarah Imhoff
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Myriam Paquette
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Olivier Le Blanc
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Simon Malenfant
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
| | - Samuel J E Lucas
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom.,Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Damian M Bailey
- Neurovascular Research Laboratory Faculty of Life Sciences and Education University of South Wales, South Wales, United Kingdom.,Faculty of Medicine, Reichwald Health Sciences Centre University of British Columbia-Okanagan, Kelowna British Columbia, Canada
| | - Jonathan D Smirl
- Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada .,Research center of the Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada
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37
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Cognitive Function and Dynamic Cerebral Blood Flow Regulation in Multiple Concussions. Asian J Sports Med 2018. [DOI: 10.5812/asjsm.67660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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38
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The influence of the carotid baroreflex on dynamic regulation of cerebral blood flow and cerebral tissue oxygenation in humans at rest and during exercise. Eur J Appl Physiol 2018; 118:959-969. [PMID: 29497836 DOI: 10.1007/s00421-018-3831-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 02/09/2018] [Indexed: 10/17/2022]
Abstract
PURPOSE This preliminary study tested the hypothesis that the carotid baroreflex (CBR) mediated sympathoexcitation regulates cerebral blood flow (CBF) at rest and during dynamic exercise. METHODS In seven healthy subjects (26 ± 1 years), oscillatory neck pressure (NP) stimuli of + 40 mmHg were applied to the carotid baroreceptors at a pre-determined frequency of 0.1 Hz at rest, low (10 ± 1W), and heavy (30 ± 3W) exercise workloads (WLs) without (control) and with α - 1 adrenoreceptor blockade (prazosin). Spectral power analysis of the mean arterial blood pressure (MAP), mean middle cerebral artery blood velocity (MCAV), and cerebral tissue oxygenation index (ScO2) in the low-frequency range (0.07-0.20 Hz) was estimated to examine NP stimuli responses. RESULTS From rest to heavy exercise, WLs resulted in a greater than three-fold increase in MCAV power (42 ± 23.8-145.2 ± 78, p < 0.01) and an almost three-fold increase in ScO2 power (0.51 ± 0.3-1.53 ± 0.8, p = 0.01), even though there were no changes in MAP power (from 24.5 ± 21 to 22.9 ± 11.9) with NP stimuli. With prazosin, the overall MAP (p = 0.0017), MCAV (p = 0.019), and ScO2 (p = 0.049) power was blunted regardless of the exercise conditions. Prazosin blockade resulted in increases in the Tf gain index between MAP and MCAV compared to the control (p = 0.03). CONCLUSION CBR-mediated changes in sympathetic activity contribute to dynamic regulation of the cerebral vasculature and CBF at rest and during dynamic exercise in humans.
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Brassard P, Tymko MM, Ainslie PN. Sympathetic control of the brain circulation: Appreciating the complexities to better understand the controversy. Auton Neurosci 2017; 207:37-47. [DOI: 10.1016/j.autneu.2017.05.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 05/03/2017] [Accepted: 05/04/2017] [Indexed: 12/24/2022]
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40
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Olver TD, Hiemstra JA, Edwards JC, Schachtman TR, Heesch CM, Fadel PJ, Laughlin MH, Emter CA. Loss of Female Sex Hormones Exacerbates Cerebrovascular and Cognitive Dysfunction in Aortic Banded Miniswine Through a Neuropeptide Y-Ca 2+-Activated Potassium Channel-Nitric Oxide Mediated Mechanism. J Am Heart Assoc 2017; 6:JAHA.117.007409. [PMID: 29089345 PMCID: PMC5721796 DOI: 10.1161/jaha.117.007409] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Background Postmenopausal women represent the largest cohort of patients with heart failure with preserved ejection fraction, and vascular dementia represents the most common form of dementia in patients with heart failure with preserved ejection fraction. Therefore, we tested the hypotheses that the combination of cardiac pressure overload (aortic banding [AB]) and the loss of female sex hormones (ovariectomy [OVX]) impairs cerebrovascular control and spatial memory. Methods and Results Female Yucatan miniswine were separated into 4 groups (n=7 per group): (1) control, (2) AB, (3) OVX, and (4) AB‐OVX. Pigs underwent OVX and AB at 7 and 8 months of age, respectively. At 14 months, cerebral blood flow velocity and spatial memory (spatial hole‐board task) were lower in the OVX groups (P<0.05), with significant impairments in the AB‐OVX group (P<0.05). Resting carotid artery β stiffness and vascular resistance during central hypovolemia were increased in the AB‐OVX group (P<0.05), and blood flow recovery after central hypovolemia was reduced in both OVX groups (P<0.05). Isolated pial artery (pressure myography) vasoconstriction to neuropeptide Y was greatest in the AB‐OVX group (P<0.05), and vasodilation to the Ca2+‐activated potassium channel α‐subunit agonist NS‐1619 was impaired in both AB groups (P<0.05). The ratio of phosphorylated endothelial nitric oxide synthase:total endothelial nitric oxide synthase was depressed and Ca2+‐activated potassium channel α‐subunit protein was increased in AB groups (P<0.05). Conclusions Mechanistically, impaired cerebral blood flow control in experimental heart failure may be the result of heightened neuropeptide Y–induced vasoconstriction along with reduced vasodilation associated with decreased Ca2+‐activated potassium channel function and impaired nitric oxide signaling, the effects of which are exacerbated in the absence of female sex hormones.
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Affiliation(s)
- T Dylan Olver
- Department of Biomedical Sciences, University of Missouri, Columbia, MO
| | | | - Jenna C Edwards
- Department of Biomedical Sciences, University of Missouri, Columbia, MO
| | - Todd R Schachtman
- Department of Psychological Sciences, University of Missouri, Columbia, MO
| | - Cheryl M Heesch
- Department of Biomedical Sciences, University of Missouri, Columbia, MO.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO
| | - Paul J Fadel
- College of Nursing and Health Innovation, University of Texas at Arlington, TX
| | - M Harold Laughlin
- Department of Biomedical Sciences, University of Missouri, Columbia, MO.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO.,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Craig A Emter
- Department of Biomedical Sciences, University of Missouri, Columbia, MO
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41
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Witter T, Tzeng YC, O'Donnell T, Kusel J, Walker B, Berry M, Taylor CE. Inter-individual Relationships between Sympathetic Arterial Baroreflex Function and Cerebral Perfusion Control in Healthy Males. Front Neurosci 2017; 11:457. [PMID: 28860964 PMCID: PMC5559461 DOI: 10.3389/fnins.2017.00457] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 07/28/2017] [Indexed: 12/29/2022] Open
Abstract
Maintenance of adequate cerebral perfusion during normal physiological challenges requires integration between cerebral blood flow (CBF) and systemic blood pressure control mechanisms. Previous studies have shown that cardiac baroreflex sensitivity (BRS) is inversely related to some measures of cerebral autoregulation. However, interactions between the sympathetic arterial baroreflex and cerebral perfusion control mechanisms have not been explored. To determine the nature and magnitude of these interactions we measured R–R interval, blood pressure, CBF velocity, and muscle sympathetic nerve activity (MSNA) in 11 healthy young males. Sympathetic BRS was estimated using modified Oxford method as the relationship between beat-to-beat diastolic blood pressure (DBP) and MSNA. Integrated control of CBF was quantified using transfer function analysis (TFA) metrics derived during rest and Tieck's autoregulatory index following bilateral thigh cuff deflation. Sympathetic BRS during modified Oxford trials was significantly related to autoregulatory index (r = 0.64, p = 0.03). Sympathetic BRS during spontaneous baseline was significantly related to transfer function gain (r = −0.74, p = 0.01). A more negative value for sympathetic BRS indicates more effective arterial baroreflex regulation, and a lower transfer function gain reflects greater cerebral autoregulation. Therefore, these findings indicate that males with attenuated CBF regulation have greater sympathetic BRS (and vice versa), consistent with compensatory interactions between blood pressure and cerebral perfusion control mechanisms.
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Affiliation(s)
- Trevor Witter
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Yu-Chieh Tzeng
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Terry O'Donnell
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Jessica Kusel
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Bridget Walker
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Mary Berry
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Chloe E Taylor
- School of Science and Health, Western Sydney UniversitySydney, NSW, Australia.,School of Medicine, Western Sydney UniversitySydney, NSW, Australia
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42
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Effect of Qigong exercise on cognitive function, blood pressure and cardiorespiratory fitness in healthy middle-aged subjects. Complement Ther Med 2017; 33:39-45. [DOI: 10.1016/j.ctim.2017.05.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 04/25/2017] [Accepted: 05/24/2017] [Indexed: 11/22/2022] Open
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43
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Ogoh S. Relationship between cognitive function and regulation of cerebral blood flow. J Physiol Sci 2017; 67:345-351. [PMID: 28155036 PMCID: PMC10717011 DOI: 10.1007/s12576-017-0525-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 01/23/2017] [Indexed: 12/11/2022]
Abstract
Ageing is the primary risk factor for cognitive deterioration. Given that the cerebral blood flow (CBF) or regulation of cerebral circulation is attenuated in the elderly, it could be expected that ageing-induced cognitive deterioration may be affected by a decrease in CBF as a result of brain ischemia and energy depletion. CBF regulation associated with cerebral metabolism thus likely plays an important role in the preservation of cognitive function. However, in some specific conditions (e.g. during exercise), change in CBF does not synchronize with that of cerebral metabolism. Our recent study demonstrated that cognitive function was more strongly affected by changes in cerebral metabolism than by changes in CBF during exercise. Therefore, it remains unclear how an alteration in CBF or its regulation affects cognitive function. In this review, I summarize current knowledge on previous investigations providing the possibility of an interaction between regulation of CBF or cerebral metabolism and cognitive function.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe-Shi, Saitama, 350-8585, Japan.
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Brassard P, Ferland-Dutil H, Smirl JD, Paquette M, Le Blanc O, Malenfant S, Ainslie PN. Evidence for hysteresis in the cerebral pressure-flow relationship in healthy men. Am J Physiol Heart Circ Physiol 2017; 312:H701-H704. [DOI: 10.1152/ajpheart.00790.2016] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 01/05/2017] [Accepted: 01/17/2017] [Indexed: 11/22/2022]
Abstract
The cerebrovasculature is more efficient at compensating for pharmacologically induced transient hypertension versus transient hypotension. Whether this phenomenon exists during nonpharmacologically induced hypertension and hypotension is currently unknown. We compared the percent change in mean velocity in the middle cerebral artery (MCAvmean) per percent change in mean arterial pressure (MAP) (%ΔMCAVmean/%ΔMAP) during transient hypertension and hypotension induced during squat-stand maneuvers performed at 0.05 Hz (20-s cycles) and 0.10 Hz (10-s cycles) in 58 male volunteers. %ΔMCAvmean/%ΔMAP was attenuated by 25% ( P = 0.03, 0.05 Hz) and 47% ( P < 0.0001, 0.10 Hz) during transient hypertension versus hypotension. Thus, these findings indicate that the brain in healthy men is better adapted to compensate for physiologically relevant transient hypertension than hypotension. NEW & NOTEWORTHY The novel finding of this study is that the change in middle cerebral artery mean flow velocity is attenuated during hypertension compared with hypotension physiologically induced by oscillations in blood pressure in men. These results support that the human brain is more effective at compensating for transient hypertension than hypotension.
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Affiliation(s)
- Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, Québec, Canada; and
| | - Hélène Ferland-Dutil
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, Québec, Canada; and
| | - Jonathan D. Smirl
- Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Myriam Paquette
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, Québec, Canada; and
| | - Olivier Le Blanc
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, Québec, Canada; and
| | - Simon Malenfant
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec City, Québec, Canada; and
| | - Philip N. Ainslie
- Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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45
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Garrett ZK, Pearson J, Subudhi AW. Postural effects on cerebral blood flow and autoregulation. Physiol Rep 2017; 5:5/4/e13150. [PMID: 28242827 PMCID: PMC5328778 DOI: 10.14814/phy2.13150] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Revised: 01/10/2017] [Accepted: 01/13/2017] [Indexed: 11/24/2022] Open
Abstract
Cerebral autoregulation (CA) is thought to maintain relatively constant cerebral blood flow (CBF) across normal blood pressures. To determine if postural changes alter CA, we measured cerebral blood flow velocity (CBFv) in the middle cerebral arteries, mean arterial blood pressure (MABP), cardiac output (Q), and end‐tidal carbon dioxide (PETCO2) in 18 healthy individuals (11 female and seven male; 26 ± 9 years) during repeated periods of supine and seated rest. Multiple regression was used to evaluate the influence of PETCO2, MABP, Q, and hydrostatic pressure on CBFv. Static CA was assessed by evaluating absolute changes in steady‐state CBFv. Dynamic CA was assessed by transfer function analysis of the CBFv response to spontaneous oscillations in MABP. In the seated versus supine posture, MABP (67.2 ± 7.2 vs. 84.2 ± 12.1 mmHg; P < 0.001), CBFv (55.2 ± 9.1 vs. 63.6 ± 10.6 cm/sec; P < 0.001) and PETCO2 (29.1 ± 2.6 vs. 30.9 ± 2.3 mmHg; P < 0.001) were reduced. Changes in CBFv were not explained by variance in PETCO2, MABP, Q, or hydrostatic pressure. A reduction in MABP to CBFv transfer function gain while seated (P < 0.01) was explained by changes in the power spectrum of MABP, not CBFv. Our findings suggest that changes in steady‐state cerebral hemodynamics between postures do not appear to have a large functional consequence on the dynamic regulation of CBF.
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Affiliation(s)
- Zachary K Garrett
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, Colorado
| | - James Pearson
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, Colorado
| | - Andrew W Subudhi
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, Colorado
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Wecht JM, Weir JP, Radulovic M, Bauman WA. Effects of midodrine and L-NAME on systemic and cerebral hemodynamics during cognitive activation in spinal cord injury and intact controls. Physiol Rep 2016; 4:4/3/e12683. [PMID: 26869679 PMCID: PMC4758920 DOI: 10.14814/phy2.12683] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
We previously showed that increases in mean arterial pressure (MAP) following administration of midodrine hydrochloride (MH) and nitro‐L‐arginine methyl ester (L‐NAME) resulted in increased mean cerebral blood flow velocity (MFV) during head‐up tilt in hypotensive individuals with spinal cord injury (SCI) and question if this same association was evident during cognitive activation. Herein, we report MAP and MFV during two serial subtraction tasks (SSt) given before (predrug) and after (postdrug) administration of MH; (10 mg), L‐NAME (1 mg/kg) or no drug (ND) in 15 subjects with SCI compared to nine able‐bodied (AB) controls. Three‐way factorial analysis of variance (ANOVA) models were used to determine significant main and interaction effects for group (SCI, AB), visit (MH, L‐NAME, ND), and time (predrug, postdrug) for MAP and MFV during the two SSt. The three‐way interaction was significant for MAP (F = 4.262; P = 0.020); both MH (30 ± 26 mmHg; P < 0.05) and L‐NAME (27 ± 22 mmHg; P < 0.01) significantly increased MAP in the SCI group, but not in the AB group. There was a significant visit by time interaction for MFV suggesting an increase from predrug to postdrug following L‐NAME (6 ± 8 cm/sec; P < 0.05) and MH (4 ± 7 cm/sec; P < 0.05), regardless of study group, with little change following ND (3 ± 3 cm/sec). The relationship between change in MAP and MFV was significant in the SCI group following administration of MH (r2 = 0.38; P < 0.05) and L‐NAME (r2 = 0.32; P < 0.05). These antihypotensive agents, at the doses tested, raised MAP, which was associated with an increase MFV during cognitive activation in hypotensive subjects with SCI.
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Affiliation(s)
- Jill M Wecht
- VA RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, New York The Medical Service, James J. Peters VAMC, Bronx New York Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York
| | - Joseph P Weir
- Department of Health, Sport and Exercise Sciences, The University of Kansas, Lawrence, Kansas
| | - Miroslav Radulovic
- VA RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, New York The Medical Service, James J. Peters VAMC, Bronx New York Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York
| | - William A Bauman
- VA RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, New York The Medical Service, James J. Peters VAMC, Bronx New York Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York
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Saleem S, Teal PD, Kleijn WB, Ainslie PN, Tzeng YC. Identification of human sympathetic neurovascular control using multivariate wavelet decomposition analysis. Am J Physiol Heart Circ Physiol 2016; 311:H837-48. [DOI: 10.1152/ajpheart.00254.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/16/2016] [Indexed: 02/07/2023]
Abstract
The dynamic regulation of cerebral blood flow (CBF) is thought to involve myogenic and chemoreflex mechanisms, but the extent to which the sympathetic nervous system also plays a role remains debated. Here we sought to identify the role of human sympathetic neurovascular control by examining cerebral pressure-flow relations using linear transfer function analysis and multivariate wavelet decomposition analysis that explicitly accounts for the confounding effects of dynamic end-tidal Pco2 (PetCO2) fluctuations. In 18 healthy participants randomly assigned to the α1-adrenergic blockade group ( n = 9; oral Prazosin, 0.05 mg/kg) or the placebo group ( n = 9), we recorded blood pressure, middle cerebral blood flow velocity, and breath-to-breath PetCO2. Analyses showed that the placebo administration did not alter wavelet phase synchronization index (PSI) values, whereas sympathetic blockade increased PSI for frequency components ≤0.03 Hz. Additionally, three-way interaction effects were found for PSI change scores, indicating that the treatment response varied as a function of frequency and whether PSI values were PetCO2 corrected. In contrast, sympathetic blockade did not affect any linear transfer function parameters. These data show that very-low-frequency CBF dynamics have a composite origin involving, not only nonlinear and nonstationary interactions between BP and PetCO2, but also frequency-dependent interplay with the sympathetic nervous system.
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Affiliation(s)
- Saqib Saleem
- School of Engineering and Computer Science, Victoria University of Wellington, Wellington, New Zealand
- Interdisciplinary Neuroprotection Research Group, Centre for Translational Physiology, University of Otago, Wellington, New Zealand
| | - Paul D. Teal
- School of Engineering and Computer Science, Victoria University of Wellington, Wellington, New Zealand
| | - W. Bastiaan Kleijn
- School of Engineering and Computer Science, Victoria University of Wellington, Wellington, New Zealand
| | - Philip N. Ainslie
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Yu-Chieh Tzeng
- Interdisciplinary Neuroprotection Research Group, Centre for Translational Physiology, University of Otago, Wellington, New Zealand
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Racosta JM, Kimpinski K. Autonomic function and brain volume. Clin Auton Res 2016; 26:377-383. [PMID: 27568208 DOI: 10.1007/s10286-016-0380-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/18/2016] [Indexed: 12/11/2022]
Abstract
OBJECTIVE The aim of this study is to review the evidence on the role of the autonomic nervous system as a determinant of brain volume. Brain volume measures have gained increasing attention given its biological importance, particularly as a measurement of neurodegeneration. METHODS Using an integrative approach, we reviewed publications addressing the anatomical and physiological characteristics of brain autonomic innervation focusing on evidence from diverse clinical populations with respect to brain volume. RESULTS Multiple mechanisms contribute to changes in brain volume. Autonomic influence on cerebral blood volume is of significant interest. CONCLUSION We suggest a role for the autonomic innervation of brain vessels in fluctuations of cerebral blood volume. Further investigation in several clinical populations including multiple sclerosis is warranted to understand the specific role of parenchyma versus blood vessels changes on final brain volume.
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Affiliation(s)
- Juan M Racosta
- Department of Clinical Neurological Sciences, London Health Sciences Centre, University Hospital, London, ON, Canada.
- Schulich School of Medicine and Dentistry, Western University, 339 Windermere Road, London, ON, Canada.
| | - Kurt Kimpinski
- Department of Clinical Neurological Sciences, London Health Sciences Centre, University Hospital, London, ON, Canada
- Schulich School of Medicine and Dentistry, Western University, 339 Windermere Road, London, ON, Canada
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Phillips AA, Hansen A, Krassioukov AV. In with the new and out with the old: enter multivariate wavelet decomposition, exit transfer function. Am J Physiol Heart Circ Physiol 2016; 311:H735-7. [PMID: 27473940 DOI: 10.1152/ajpheart.00512.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Aaron A Phillips
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada; International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, Canada; Department of Medicine, Division of Physical Medicine and Rehabilitation, University of British Columbia, Vancouver, Canada; and
| | - Alex Hansen
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Andrei V Krassioukov
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada; International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, Canada; Department of Medicine, Division of Physical Medicine and Rehabilitation, University of British Columbia, Vancouver, Canada; and GF Strong Rehabilitation Centre, Vancouver Health Authority, Vancouver, Canada
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Ogoh S, Sørensen H, Hirasawa A, Sasaki H, Washio T, Hashimoto T, Bailey DM, Secher NH. Dynamic cerebral autoregulation is unrelated to decrease in external carotid artery blood flow during acute hypotension in healthy young men. Exp Physiol 2016; 101:1040-9. [PMID: 27228963 DOI: 10.1113/ep085772] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/19/2016] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Dynamic cerebral autoregulation (CA) is impaired by sympathetic blockade, and the external carotid artery (ECA) vascular bed may prevent adequate internal carotid artery blood flow. We examined whether α1 -receptor blockade-induced attenuation of dynamic CA is related to reduced ECA vasoconstriction. What is the main finding and its importance? α1 -Receptor blockade attenuated dynamic CA, but in contrast to our hypothesis did not affect the ECA blood flow response to acute hypotension. These findings suggest that the recovery of cerebral blood flow during acute hypotension is unrelated to vasoconstriction within the ECA territory. External carotid artery (ECA) vasoconstriction may defend internal carotid artery (ICA) blood flow during acute hypotension. We hypothesized that the α1 -receptor blockade-induced delay in ICA recovery to the baseline level from acute hypoperfusion is related to attenuated ECA vasoconstriction. The ICA and ECA blood flow were determined by duplex ultrasound during thigh-cuff release-induced acute hypotension while the α1 -receptor blocker prazosin [1 mg (20 kg)(-1) ] was administered to nine seated young healthy men. Both ICA (mean ± SD; by 17 ± 8%, P = 0.005) and ECA (by 37 ± 15%, P < 0.001) blood flow decreased immediately after occluded thigh-cuff release, with a more rapid ICA blood flow recovery to the baseline level (9 ± 5 s) than for the ECA blood flow (17 ± 5 s; P = 0.019). The ICA blood flow recovery from hypoperfusion was delayed with prazosin (17 ± 4 s versus control 9 ± 5 s, P = 0.006), whereas ECA recovery remained unchanged (P = 0.313) despite a similar reduction in mean arterial pressure (-20 ± 4 mmHg versus control -23 ± 7 mmHg, P = 0.148). These findings suggest that α1 -receptor blockade-induced attenuation of the ICA blood flow response to acute hypotension is unrelated to the reduction in ECA blood flow. The sympathetic nervous system via the ECA vascular bed does not contribute to dynamic CA during acute hypotension.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Henrik Sørensen
- The Copenhagen Muscle Research Centre, Department of Anesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Ai Hirasawa
- Advanced Triage Team, Kyorin University School of Medicine, Mitaka-Shi, Tokyo, Japan
| | - Hiroyuki Sasaki
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Takuro Washio
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Takeshi Hashimoto
- Graduate School of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Damian M Bailey
- Neurovascular Research Laboratory, Research Institute of Health and Wellbeing, Faculty of Life Sciences and Education, University of South Wales, UK
| | - Niels H Secher
- The Copenhagen Muscle Research Centre, Department of Anesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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