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Sagirov AF, Sergeev TV, Shabrov AV, Yurov AY, Guseva NL, Agapova EA. Postural influence on intracranial fluid dynamics: an overview. J Physiol Anthropol 2023; 42:5. [PMID: 37055862 PMCID: PMC10100470 DOI: 10.1186/s40101-023-00323-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 04/01/2023] [Indexed: 04/15/2023] Open
Abstract
This review focuses on the effects of different body positions on intracranial fluid dynamics, including cerebral arterial and venous flow, cerebrospinal fluid (CSF) hydrodynamics, and intracranial pressure (ICP). It also discusses research methods used to quantify these effects. Specifically, the implications of three types of body positions (orthostatic, supine, and antiorthostatic) on cerebral blood flow, venous outflow, and CSF circulation are explored, with a particular emphasis on cerebrovascular autoregulation during microgravity and head-down tilt (HDT), as well as posture-dependent changes in cerebral venous and CSF flow, ICP, and intracranial compliance (ICC). The review aims to provide a comprehensive analysis of intracranial fluid dynamics during different body positions, with the potential to enhance our understanding of intracranial and craniospinal physiology.
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Affiliation(s)
- Arlan Faritovich Sagirov
- Department of Ecological Physiology, Federal State Budgetary Scientific Institution "Institute of Experimental Medicine", 12 Academic Pavlov St, Saint-Petersburg, 197022, Russia.
| | - Timofey Vladimirovich Sergeev
- Department of Ecological Physiology, Federal State Budgetary Scientific Institution "Institute of Experimental Medicine", 12 Academic Pavlov St, Saint-Petersburg, 197022, Russia
| | - Aleksandr Vladimirovich Shabrov
- Department of Ecological Physiology, Federal State Budgetary Scientific Institution "Institute of Experimental Medicine", 12 Academic Pavlov St, Saint-Petersburg, 197022, Russia
| | - Andrey Yur'evich Yurov
- Department of Ecological Physiology, Federal State Budgetary Scientific Institution "Institute of Experimental Medicine", 12 Academic Pavlov St, Saint-Petersburg, 197022, Russia
| | - Nadezhda Leonidovna Guseva
- Department of Ecological Physiology, Federal State Budgetary Scientific Institution "Institute of Experimental Medicine", 12 Academic Pavlov St, Saint-Petersburg, 197022, Russia
| | - Elizaveta Aleksandrovna Agapova
- Department of Ecological Physiology, Federal State Budgetary Scientific Institution "Institute of Experimental Medicine", 12 Academic Pavlov St, Saint-Petersburg, 197022, Russia
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Sakamoto R, Sato K, Ogoh S, Kamoda T, Neki T, Katayose M, Iwamoto E. Dynamic resistance exercise-induced pressor response does not alter hypercapnia-induced cerebral vasodilation in young adults. Eur J Appl Physiol 2023; 123:781-796. [PMID: 36454281 DOI: 10.1007/s00421-022-05096-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 11/12/2022] [Indexed: 12/05/2022]
Abstract
Excessive arterial pressure elevation induced by resistance exercise (RE) attenuates peripheral vasodilatory function, but its effect on cerebrovascular function is unknown. We aimed to evaluate the effect of different pressor responses to RE on hypercapnia-induced vasodilation of the internal carotid artery (ICA), an index of cerebrovascular function. To manipulate pressor responses to RE, 15 healthy young adults (11M/4F) performed two RE: high intensity with low repetitions (HL) and low intensity with high repetitions (LH) dynamic knee extension. ICA dilation, induced by 3 min of hypercapnia, was measured before and 10 min after RE using Doppler ultrasound. HL exercise elicited a greater pressor response than LH exercise. In relaxation phases of RE, ICA blood velocity increased in both HL and LH trials. However, ICA shear rate did not significantly increase in either trial (P = 0.06). Consequently, neither exercise altered post-exercise hypercapnia-induced ICA dilation (HL, 3.9 ± 1.9% to 5.1 ± 1.7%; LH, 4.6 ± 1.4% to 4.8 ± 1.8%; P > 0.05 for all). When viewed individually, the changes in ICA shear rate were positively correlated with changes in end-tidal partial pressure of carbon dioxide (PETCO2) (r = 0.46, P < 0.01) than with mean arterial pressure (r = 0.32, P = 0.02). These findings suggest that the effects of RE-induced pressor response on cerebrovascular function may be different from peripheral arteries. An increase in PETCO2 during the relaxation phase may play a more crucial role than elevated pressure in increasing cerebral shear during dynamic RE.
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Affiliation(s)
- Rintaro Sakamoto
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
- Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Kohei Sato
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe, Japan
| | - Tatsuki Kamoda
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | - Toru Neki
- Department of Physical Therapy, School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | - Masaki Katayose
- Department of Physical Therapy, School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | - Erika Iwamoto
- Department of Physical Therapy, School of Health Sciences, Sapporo Medical University, Sapporo, Japan.
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3
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Sarafis ZK, Squair JW, Barak OF, Coombs GB, Soriano JE, Larkin-Kaiser KA, Lee AHX, Hansen A, Vodopic M, Romac R, Grant C, Charbonneau R, Mijacika T, Krassioukov AV, Ainslie PN, Dujic Z, Phillips AA. Common carotid artery responses to the cold-pressor test are impaired in individuals with cervical spinal cord injury. Am J Physiol Heart Circ Physiol 2022; 323:H1311-H1322. [PMID: 36367686 DOI: 10.1152/ajpheart.00261.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Cervical spinal cord injury (SCI) leads to autonomic cardiovascular dysfunction that underlies the three- to fourfold elevated risk of cardiovascular disease in this population. Reduced common carotid artery (CCA) dilatory responsiveness during the cold-pressor test (CPT) is associated with greater cardiovascular disease risk and progression. The cardiovascular and CCA responses to the CPT may provide insight into cardiovascular autonomic dysfunction and cardiovascular disease risk in individuals with cervical SCI. Here, we used CPT to perturb the autonomic nervous system in 14 individuals with cervical SCI and 12 uninjured controls, while measuring cardiovascular responses and CCA diameter. The CCA diameter responses were 55% impaired in those with SCI compared with uninjured controls (P = 0.019). The CCA flow, velocity, and shear response to CPT were reduced in SCI by 100% (P < 0.001), 113% (P = 0.001), and 125% (P = 0.002), respectively. The association between mean arterial pressure and CCA dilation observed in uninjured individuals (r = 0.54, P = 0.004) was absent in the SCI group (r = 0.22, P = 0.217). Steady-state systolic blood pressure (P = 0.020), heart rate (P = 0.003), and cardiac contractility (P < 0.001) were reduced in those with cervical SCI, whereas total peripheral resistance was increased compared with uninjured controls (P = 0.042). Relative cerebral blood velocity responses to CPT were increased in the SCI group and reduced in controls (middle cerebral artery, P = 0.010; posterior cerebral artery, P = 0.026). The CCA and cardiovascular responsiveness to CPT are impaired in those with cervical SCI.NEW & NOTEWORTHY This is the first study demonstrating that CCA responses during CPT are suppressed in SCI. Specifically, CCA diameter, flow, velocity, and shear rate were reduced. The relationship between changes in MAP and CCA dilatation in response to CPT was absent in individuals with SCI, despite similar cardiovascular activation between SCI and uninjured controls. These findings support the notion of elevated cardiovascular disease risk in SCI and that the cardiovascular responses to environmental stimuli are impaired.
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Affiliation(s)
- Zoe K Sarafis
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jordan W Squair
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,RESTORE.network, Departments of Physiology and Pharmacology, Cardiac Sciences and Clinical Neurosciences, Biomedical Engineering, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,MD/PhD Training Program, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Experimental Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Otto F Barak
- Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia
| | - Geoff B Coombs
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Jan Elaine Soriano
- RESTORE.network, Departments of Physiology and Pharmacology, Cardiac Sciences and Clinical Neurosciences, Biomedical Engineering, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Kelly A Larkin-Kaiser
- RESTORE.network, Departments of Physiology and Pharmacology, Cardiac Sciences and Clinical Neurosciences, Biomedical Engineering, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Amanda H X Lee
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Experimental Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alex Hansen
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Maro Vodopic
- Department of Neurology, General Hospital, Dubrovnik, Croatia
| | - Rinaldo Romac
- Department of Neurology, Clinical Hospital Center, Split, Croatia
| | - Christopher Grant
- Division of Physical Medicine and Rehabilitation, Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Rebecca Charbonneau
- Division of Physical Medicine and Rehabilitation, Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Tanja Mijacika
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Andrei V Krassioukov
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Division of Physical Medicine and Rehabilitation, University of British Columbia, Vancouver, British Columbia, Canada.,GF Strong Rehabilitation Centre, Vancouver, British Columbia, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Zeljko Dujic
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Aaron A Phillips
- RESTORE.network, Departments of Physiology and Pharmacology, Cardiac Sciences and Clinical Neurosciences, Biomedical Engineering, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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Ogoh S, Hirasawa A, Shibata S. Influence of head-up tile and lower body negative pressure on the internal jugular vein. Physiol Rep 2022; 10:e15248. [PMID: 35581747 PMCID: PMC9114655 DOI: 10.14814/phy2.15248] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 06/15/2023] Open
Abstract
Head-up tilt (HUT)-induced gravitational stress causes collapse of the internal jugular vein (IJV) by decreasing central blood volume and through mass-effect from the surrounding tissues. Besides HUT, lower body negative pressure (LBNP) is used to stimulate orthostatic stress as an experimental model. Compared to HUT, LBNP has less of a gravitational effect because of the supine position; therefore, we hypothesized that LBNP causes less of a decrease in the cross-sectional area of the IJV compared to HUT. We tested the hypothesis by measuring the cross-sectional area of the IJV using B-mode ultrasonography while inducing orthostatic stress at levels of -40 mmHg LBNP and 60° HUT. The cross-sectional area of IJV decreased from the resting baseline during both LBNP and HUT trials, but the LBNP-induced decrease in the cross-sectional area of IJV was smaller than that of HUT (right, -45% ± 49% vs. -78% ± 27%, p = 0.008; left, -49% ± 27% vs. -78% ± 20%, p = 0.004). Since changes in venous outflow may affect cerebral arterial circulation, the findings of the present study suggest that orthostatic stress induced by different techniques modulates cerebral blood flow regulation through its effect on venous outflow.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical EngineeringToyo UniversitySaitamaJapan
- Neurovascular Research LaboratoryFaculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| | - Ai Hirasawa
- Department of Health and WelfareFaculty of Health SciencesKyorin UniversityTokyoJapan
| | - Shigeki Shibata
- Department of Physical TherapyFaculty of Health ScienceKyorin UniversityTokyoJapan
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Anderson GK, Rosenberg AJ, Barnes HJ, Bird J, Pentz B, Byman BRM, Jendzjowsky N, Wilson RJA, Day TA, Rickards CA. Peaks and valleys: oscillatory cerebral blood flow at high altitude protects cerebral tissue oxygenation. Physiol Meas 2021; 42:10.1088/1361-6579/ac0593. [PMID: 34038879 PMCID: PMC11046575 DOI: 10.1088/1361-6579/ac0593] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 05/26/2021] [Indexed: 01/21/2023]
Abstract
Introduction.Oscillatory patterns in arterial pressure and blood flow (at ∼0.1 Hz) may protect tissue oxygenation during conditions of reduced cerebral perfusion and/or hypoxia. We hypothesized that inducing oscillations in arterial pressure and cerebral blood flow at 0.1 Hz would protect cerebral blood flow and cerebral tissue oxygen saturation during exposure to a combination of simulated hemorrhage and sustained hypobaric hypoxia.Methods.Eight healthy human subjects (4 male, 4 female; 30.1 ± 7.6 year) participated in two experiments at high altitude (White Mountain, California, USA; altitude, 3800 m) following rapid ascent and 5-7 d of acclimatization: (1) static lower body negative pressure (LBNP, control condition) was used to induce central hypovolemia by reducing chamber pressure to -60 mmHg for 10 min(0 Hz), and; (2) oscillatory LBNP where chamber pressure was reduced to -60 mmHg, then oscillated every 5 s between -30 mmHg and -90 mmHg for 10 min(0.1 Hz). Measurements included arterial pressure, internal carotid artery (ICA) blood flow, middle cerebral artery velocity (MCAv), and cerebral tissue oxygen saturation (ScO2).Results.Forced 0.1 Hz oscillations in mean arterial pressure and mean MCAv were accompanied by a protection of ScO2(0.1 Hz: -0.67% ± 1.0%; 0 Hz: -4.07% ± 2.0%;P = 0.01). However, the 0.1 Hz profile did not protect against reductions in ICA blood flow (0.1 Hz: -32.5% ± 4.5%; 0 Hz: -19.9% ± 8.9%;P = 0.24) or mean MCAv (0.1 Hz: -18.5% ± 3.4%; 0 Hz: -15.3% ± 5.4%;P = 0.16).Conclusions.Induced oscillatory arterial pressure and cerebral blood flow led to protection of ScO2during combined simulated hemorrhage and sustained hypoxia. This protection was not associated with the preservation of cerebral blood flow suggesting preservation of ScO2may be due to mechanisms occurring within the microvasculature.
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Affiliation(s)
- Garen K Anderson
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America
- Co-first authorship
| | - Alexander J Rosenberg
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America
- Co-first authorship
| | - Haley J Barnes
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Jordan Bird
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Brandon Pentz
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Britta R M Byman
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Nicholas Jendzjowsky
- Institute of Respiratory Medicine & Exercise Physiology, The Lundquist Institute at UCLA Harbor Medical, Torrance, CA, United States of America
| | - Richard J A Wilson
- Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute; Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Trevor A Day
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Caroline A Rickards
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America
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Lie SL, Hisdal J, Høiseth LØ. Cerebral blood flow velocity during simultaneous changes in mean arterial pressure and cardiac output in healthy volunteers. Eur J Appl Physiol 2021; 121:2207-2217. [PMID: 33890157 PMCID: PMC8260418 DOI: 10.1007/s00421-021-04693-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 04/15/2021] [Indexed: 02/03/2023]
Abstract
Purpose Cerebral blood flow (CBF) needs to be precisely controlled to maintain brain functions. While previously believed to be autoregulated and near constant over a wide blood pressure range, CBF is now understood as more pressure passive. However, there are still questions regarding the integrated nature of CBF regulation and more specifically the role of cardiac output. Our aim was, therefore, to explore the effects of MAP and cardiac output on CBF in a combined model of reduced preload and increased afterload. Method 16 healthy volunteers were exposed to combinations of different levels of simultaneous lower body negative pressure and isometric hand grip. We measured blood velocity in the middle cerebral artery (MCAV) and internal carotid artery (ICAV) by Doppler ultrasound, and cerebral oxygen saturation (ScO2) by near-infrared spectroscopy, as surrogates for CBF. The effect of changes in MAP and cardiac output on CBF was estimated with mixed multiple regression. Result Both MAP and cardiac output had independent effects on MCAV, ICAV and ScO2. For ICAV and ScO2 there was also a statistically significant interaction effect between MAP and cardiac output. The estimated effect of a change of 10 mmHg in MAP on MCAV was 3.11 cm/s (95% CI 2.51–3.71, P < 0.001), and the effect of a change of 1 L/min in cardiac output was 3.41 cm/s (95% CI 2.82–4.00, P < 0.001). Conclusion The present study indicates that during reductions in cardiac output, both MAP and cardiac output have independent effects on CBF. Supplementary Information The online version contains supplementary material available at 10.1007/s00421-021-04693-6.
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Affiliation(s)
- Sole Lindvåg Lie
- Faculty of Medicine, University of Oslo, Oslo, Norway. .,Section of Vascular Investigations, Department of Vascular Surgery, Oslo University Hospital, 0424, Oslo, Norway.
| | - Jonny Hisdal
- Faculty of Medicine, University of Oslo, Oslo, Norway.,Section of Vascular Investigations, Department of Vascular Surgery, Oslo University Hospital, 0424, Oslo, Norway
| | - Lars Øivind Høiseth
- Department of Anesthesiology, Division of Emergencies and Critical Care, Oslo University Hospital, Oslo, Norway
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Aebi MR, Bourdillon N, Kunz A, Bron D, Millet GP. Specific effect of hypobaria on cerebrovascular hypercapnic responses in hypoxia. Physiol Rep 2021; 8:e14372. [PMID: 32097541 PMCID: PMC7058173 DOI: 10.14814/phy2.14372] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 01/21/2020] [Indexed: 12/14/2022] Open
Abstract
It remains unknown whether hypobaria plays a role on cerebrovascular reactivity to CO2 (CVR). The present study evaluated the putative effect of hypobaria on CVR and its influence on cerebral oxygen delivery (cDO2) in five randomized conditions (i.e., normobaric normoxia, NN, altitude level of 440 m; hypobaric hypoxia, HH at altitude levels of 3,000 m and 5,500 m; normobaric hypoxia, NH, altitude simulation of 5,500 m; and hypobaric normoxia, HN). CVR was assessed in nine healthy participants (either students in aviation or pilots) during a hypercapnic test (i.e., 5% CO2). We obtained CVR by plotting middle cerebral artery velocity versus end‐tidal CO2 pressure (PETCO2) using a sigmoid model. Hypobaria induced an increased slope in HH (0.66 ± 0.33) compared to NH (0.35 ± 0.19) with a trend in HN (0.46 ± 0.12) compared to NN (0.23 ± 0.12, p = .069). PETCO2 was decreased (22.3 ± 2.4 vs. 34.5 ± 2.8 mmHg and 19.9 ± 1.3 vs. 30.8 ± 2.2 mmHg, for HN vs. NN and HH vs. NH, respectively, p < .05) in hypobaric conditions when compared to normobaric conditions with comparable inspired oxygen pressure (141 ± 1 vs. 133 ± 3 mmHg and 74 ± 1 vs. 70 ± 2 mmHg, for NN vs. HN and NH vs. HH, respectively) During hypercapnia, cDO2 was decreased in 5,500 m HH (p = .046), but maintained in NH when compared to NN. To conclude, CVR seems more sensitive (i.e., slope increase) in hypobaric than in normobaric conditions. Moreover, hypobaria potentially affected vasodilation reserve (i.e., MCAv autoregulation) and brain oxygen delivery during hypercapnia. These results are relevant for populations (i.e., aviation pilots; high‐altitude residents as miners; mountaineers) occasionally exposed to hypobaric normoxia.
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Affiliation(s)
- Mathias R Aebi
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.,Aeromedical Center (AeMC), Swiss Air Force, Dübendorf, Switzerland
| | - Nicolas Bourdillon
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.,Becare SA, Renens, Switzerland
| | - Andres Kunz
- Aeromedical Center (AeMC), Swiss Air Force, Dübendorf, Switzerland
| | - Denis Bron
- Aeromedical Center (AeMC), Swiss Air Force, Dübendorf, Switzerland
| | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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8
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The effect of hypercapnia on regional cerebral blood flow regulation during progressive lower-body negative pressure. Eur J Appl Physiol 2020; 121:339-349. [PMID: 33089364 DOI: 10.1007/s00421-020-04506-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 09/19/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE Previous work indicates that dynamic cerebral blood flow (CBF) regulation is impaired during hypercapnia; however, less is known about the impact of resting hypercapnia on regional CBF regulation during hypovolemia. Furthermore, there is disparity within the literature on whether differences between anterior and posterior CBF regulation exist during physiological stressors. We hypothesized: (a) lower-body negative pressure (LBNP)-induced reductions in cerebral blood velocity (surrogate for CBF) would be more pronounced during hypercapnia, indicating impaired CBF regulation; and (b) the anterior and posterior cerebral circulations will exhibit similar responses to LBNP. METHODS In 12 healthy participants (6 females), heart rate (electrocardiogram), mean arterial pressure (MAP; finger photoplethosmography), partial pressure of end-tidal carbon dioxide (PETCO2), middle cerebral artery blood velocity (MCAv) and posterior cerebral artery blood velocity (PCAv; transcranial Doppler ultrasound) were measured. Cerebrovascular conductance (CVC) was calculated as MCAv or PCAv indexed to MAP. Two randomized incremental LBNP protocols were conducted (- 20, - 40, - 60 and - 80 mmHg; three-minute stages), during coached normocapnia (i.e., room air), and inspired 5% hypercapnia (~ + 7 mmHg PETCO2 in normoxia). RESULTS The main findings were: (a) static CBF regulation in the MCA and PCA was similar during normocapnic and hypercapnic LBNP trials, (b) MCA and PCA CBV and CVC responded similarly to LBNP during normocapnia, but (c) PCAv and PCA CVC were reduced to a greater extent at - 60 mmHg LBNP (P = 0.029; P < 0.001) during hypercapnia. CONCLUSION CBF regulation during hypovolemia was preserved in hypercapnia, and regional differences in cerebrovascular control may exist during superimposed hypovolemia and hypercapnia.
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Barbosa TC, Young BE, Stephens BY, Nandadeva D, Kaur J, Keller DM, Fadel PJ. Functional sympatholysis is preserved in healthy young Black men during rhythmic handgrip exercise. Am J Physiol Regul Integr Comp Physiol 2020; 319:R323-R328. [PMID: 32783690 DOI: 10.1152/ajpregu.00105.2020] [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] [Indexed: 11/22/2022]
Abstract
Black men have attenuated increases in forearm vascular conductance (FVC) and forearm blood flow (FBF) during moderate- and high-intensity rhythmic handgrip exercise compared with White men, but the underlying mechanisms are unclear. Here, we tested for the first time the hypothesis that functional sympatholysis (i.e., attenuation of sympathetic vasoconstriction in the exercising muscles) is impaired in Black men compared with White men. Thirteen White and 14 Black healthy young men were studied. FBF (duplex Doppler ultrasound) and mean arterial pressure (MAP; Finometer) were measured at rest and during rhythmic handgrip exercise at 30% maximal voluntary contraction. FVC was calculated as FBF/MAP. Sympathetic activation was induced via lower body negative pressure (LBNP) at -20 Torr for 2 min at rest and from the 3rd to the 5th min of handgrip. Sympathetic vasoconstriction was assessed as percent reductions in FVC during LBNP. The groups presented similar resting FVC, FBF, and MAP. During LBNP at rest, reductions in FVC were not different between White (-35 ± 10%) and Black men (-32 ± 14%, P = 0.616), indicating similar reflex-induced sympathetic vasoconstriction. During handgrip exercise, there were minimal reductions in FVC with LBNP in either group (White: -1 ± 7%; Black: +1 ± 8%; P = 0.523), indicating functional sympatholysis in both groups. Thus, contrary to our hypothesis, our findings indicate a preserved functional sympatholysis in healthy young Black men compared with White men, suggesting that this mechanism does not appear to contribute to reduced exercise hyperemia during moderate-intensity rhythmic handgrip in this population.
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Affiliation(s)
- Thales C Barbosa
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas
| | - Benjamin E Young
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas
| | - Brandi Y Stephens
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas
| | - Damsara Nandadeva
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas
| | - Jasdeep Kaur
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas
| | - David M Keller
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas
| | - Paul J Fadel
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas
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10
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Ogoh S, Washio T, Paton JFR, Fisher JP, Petersen LG. Gravitational effects on intracranial pressure and blood flow regulation in young men: a potential shunting role for the external carotid artery. J Appl Physiol (1985) 2020; 129:901-908. [PMID: 32816640 DOI: 10.1152/japplphysiol.00369.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We sought to determine whether gravity-induced changes in intracranial pressure influence cerebral blood flow regulation. Accordingly, nine young healthy men were studied while supine (0°) and during mild changes in hydrostatic pressure induced by head-up tilt at +20° and +10° (HUT+20 and HUT+10) and head-down tilt at -20° and -10° (HDT-20, HDT-10). Blood flows were measured in the internal and external carotid and vertebral arteries (ICA, ECA, and VA). Intraocular pressure (IOP) was measured as an indicator of hydrostatic changes in intracranial pressure. A posture change from HUT+20 to HDT-20 increased IOP by +5.1 ± 1.9 mmHg (P < 0.001) and ECA blood flow (from 61.7 ± 26.1 to 87.6 ± 46.4 mL/min, P = 0.004) but did not affect ICA (P = 0.528) or VA (P = 0.101) blood flow. The increase in ECA flow correlated with the tilt angle and resultant changes in intracranial pressures (by IOP), thus indicating a passive hydrostatic gravitational dependence (r = 0.371, P = 0.012). On the contrary, ICA flow remained constant and thus well protected against moderate orthostatic stress. When ICA flow was corrected for the gravitational changes in intracranial pressures (by IOP), it demonstrated the same magnitude of gravitational dependence as ECA. These findings suggest that passive hydrostatic increases in intracranial pressure outbalance the concurrent increase in arterial feeding pressure to the brain and thus prevent cerebral hyperperfusion during HDT. The mechanism for maintaining constant cerebral flow was by increased ECA flow, thus supporting the role of these vascular beds as a shunting pathway.NEW & NOTEWORTHY We investigated whether gravity-induced changes in intracranial pressure influence cerebral blood flow regulation in young men. We recorded extra- and intracerebral blood flow during changes in posture, and data indicate that the external carotid artery may serve as an overflow pathway to prevent cerebral hyperperfusion during increases in cerebral arterial blood pressure.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Takuro Washio
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Julian F R Paton
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - James P Fisher
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Lonnie G Petersen
- Department of Biomedical Science, Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark.,Department of Radiology, University of California, San Diego, California.,Department of Mechanical and Aerospace Engineering, University of California, San Diego, California
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Samora M, Vianna LC, Carmo JC, Macedo V, Dawes M, Phillips AA, Paton JFR, Fisher JP. Neurovascular coupling is not influenced by lower body negative pressure in humans. Am J Physiol Heart Circ Physiol 2020; 319:H22-H31. [PMID: 32442032 DOI: 10.1152/ajpheart.00076.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cerebral blood flow is tightly coupled with local neuronal activation and metabolism, i.e., neurovascular coupling (NVC). Studies suggest a role of sympathetic nervous system in the regulation of cerebral blood flow. However, this is controversial, and the sympathetic regulation of NVC in humans remains unclear. Since impaired NVC has been identified in several chronic diseases associated with a heightened sympathetic activity, we aimed to determine whether reflex-mediated sympathetic activation via lower body negative pressure (LBNP) attenuates NVC in humans. NVC was assessed using a visual stimulation protocol (5 cycles of 30 s eyes closed and 30 s of reading) in 11 healthy participants (aged 24 ± 3 yr). NVC assessments were made under control conditions and during LBNP at -20 and -40 mmHg. Posterior (PCA) and middle (MCA) cerebral artery mean blood velocity (Vmean) and vertebral artery blood flow (VAflow) were simultaneously determined with cardiorespiratory variables. Under control conditions, the visual stimulation evoked a robust increase in PCAVmean (∆18.0 ± 4.5%), a moderate rise in VAflow (∆9.6 ± 4.3%), and a modest increase in MCAVmean (∆3.0 ± 1.9%). The magnitude of NVC response was not affected by mild-to-moderate LBNP (all P > 0.05 for repeated-measures ANOVA). Given the small change that occurred in partial pressure of end-tidal CO2 during LBNP, this hypocapnia condition was matched via voluntary hyperventilation in absence of LBNP in a subgroup of participants (n = 8). The mild hypocapnia during LBNP did not exert a confounding influence on the NVC response. These findings indicate that the NVC is not influenced by LBNP or mild hypocapnia in humans.NEW & NOTEWORTHY Visual stimulation evoked a robust increase in posterior cerebral artery velocity and a modest increase in vertebral artery blood flow, i.e., neurovascular coupling (NVC), which was unaffected by lower body negative pressure (LBNP) in humans. In addition, although LBNP induced a mild hypocapnia, this degree of hypocapnia in the absence of LBNP failed to modify the NVC response.
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Affiliation(s)
- Milena Samora
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.,NeuroV̇ASQ̇-Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasília, Distrito Federal, Brazil
| | - Lauro C Vianna
- NeuroV̇ASQ̇-Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasília, Distrito Federal, Brazil
| | - Jake C Carmo
- Biomechanics and Biological Signal Processing Laboratory, Faculty of Physical Education, University of Brasília, Brasília, Distrito Federal, Brazil
| | - Victor Macedo
- Biomechanics and Biological Signal Processing Laboratory, Faculty of Physical Education, University of Brasília, Brasília, Distrito Federal, Brazil
| | - Matthew Dawes
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Aaron A Phillips
- Departments of Physiology, Pharmacology, and Clinical Neurosciences, Libin Cardiovascular Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Julian F R Paton
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - James P Fisher
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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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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Witte E, Liu Y, Ward JL, Kempf KS, Whitaker A, Vidoni ED, Craig JC, Poole DC, Billinger SA. Exercise intensity and middle cerebral artery dynamics in humans. Respir Physiol Neurobiol 2019; 262:32-39. [PMID: 30710650 PMCID: PMC6393201 DOI: 10.1016/j.resp.2019.01.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 01/11/2019] [Accepted: 01/29/2019] [Indexed: 12/24/2022]
Abstract
Despite its necessity for understanding healthy brain aging, the influence of exercise intensity on cerebrovascular kinetics is currently unknown. We, therefore characterized middle cerebral artery blood flow velocity (MCAv) kinetics associated with two exercise intensities: low and moderate. We hypothesized that increasing exercise intensity would increase the MCAv amplitude response (Amp) and that age and estimated fitness (V̇O2max) would be related to Amp. Baseline (BL) values were collected for 90-seconds followed by a 6-minute exercise bout. Heart rate, end-tidal CO2, mean arterial pressure and MCAv were recorded throughout. MCAv kinetics were described by Amp, time delay (TD) and time constant (τ). Sixty-four adults completed the study. Amp was greater during moderate compared to low exercise intensity (p < 0.001) while no difference was observed in either TD (p = 0.65) or τ (p = 0.47). Amp was negatively associated with age (p < 0.01) and positively correlated with estimated V̇O2max (p < 0.01). Although Amp declines with age, maintaining higher V̇O2max may benefit the cerebrovascular response to exercise.
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Affiliation(s)
- Emily Witte
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States
| | - Yumei Liu
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States
| | - Jaimie L Ward
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States
| | - Katie S Kempf
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States
| | - Alicen Whitaker
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States
| | - Eric D Vidoni
- University of Kansas, Alzheimer's Disease Center, KU Clinical Research Center 4350 Shawnee Mission Parkway, MS 6002, Fairway, KS 66205, United States
| | - Jesse C Craig
- Kansas State University, Departments of Kinesiology, 131 Coles Hall, 920 Denison Ave, Manhattan, KS 66506, United States
| | - David C Poole
- Kansas State University, Departments of Kinesiology, 131 Coles Hall, 920 Denison Ave, Manhattan, KS 66506, United States
| | - Sandra A Billinger
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States.
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