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Broggini T, Duckworth J, Ji X, Liu R, Xia X, Mächler P, Shaked I, Munting LP, Iyengar S, Kotlikoff M, van Veluw SJ, Vergassola M, Mishne G, Kleinfeld D. Long-wavelength traveling waves of vasomotion modulate the perfusion of cortex. Neuron 2024; 112:2349-2367.e8. [PMID: 38781972 PMCID: PMC11257831 DOI: 10.1016/j.neuron.2024.04.034] [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: 10/17/2023] [Revised: 03/28/2024] [Accepted: 04/30/2024] [Indexed: 05/25/2024]
Abstract
Brain arterioles are active, multicellular complexes whose diameters oscillate at ∼ 0.1 Hz. We assess the physiological impact and spatiotemporal dynamics of vaso-oscillations in the awake mouse. First, vaso-oscillations in penetrating arterioles, which source blood from pial arterioles to the capillary bed, profoundly impact perfusion throughout neocortex. The modulation in flux during resting-state activity exceeds that of stimulus-induced activity. Second, the change in perfusion through arterioles relative to the change in their diameter is weak. This implies that the capillary bed dominates the hydrodynamic resistance of brain vasculature. Lastly, the phase of vaso-oscillations evolves slowly along arterioles, with a wavelength that exceeds the span of the cortical mantle and sufficient variability to establish functional cortical areas as parcels of uniform phase. The phase-gradient supports traveling waves in either direction along both pial and penetrating arterioles. This implies that waves along penetrating arterioles can mix, but not directionally transport, interstitial fluids.
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Affiliation(s)
- Thomas Broggini
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA; Goethe University Frankfurt, Department of Neurosurgery, 60528 Frankfurt am Main, Germany; Frankfurt Cancer Institute, Goethe University Frankfurt, 60528 Frankfurt am Main, Germany
| | - Jacob Duckworth
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Xiang Ji
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Rui Liu
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Xinyue Xia
- Halıcıoğlu Data Science Institute, University of California, San Diego, La Jolla, CA 92093, USA
| | - Philipp Mächler
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Iftach Shaked
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Leon Paul Munting
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Satish Iyengar
- Department of Statistics, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Michael Kotlikoff
- College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Susanne J van Veluw
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | | | - Gal Mishne
- Halıcıoğlu Data Science Institute, University of California, San Diego, La Jolla, CA 92093, USA
| | - David Kleinfeld
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA; Department of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA.
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Gruenewald T, Seeman TE, Choo TH, Scodes J, Snyder C, Pavlicova M, Weinstein M, Schwartz JE, Mukkamala R, Sloan RP. Cardiovascular variability, sociodemographics, and biomarkers of disease: the MIDUS study. Front Physiol 2023; 14:1234427. [PMID: 37693005 PMCID: PMC10484414 DOI: 10.3389/fphys.2023.1234427] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 08/09/2023] [Indexed: 09/12/2023] Open
Abstract
Introduction: Like heart rate, blood pressure (BP) is not steady but varies over intervals as long as months to as short as consecutive cardiac cycles. This blood pressure variability (BPV) consists of regularly occurring oscillations as well as less well-organized changes and typically is computed as the standard deviation of multiple clinic visit-to-visit (VVV-BP) measures or from 24-h ambulatory BP recordings (ABPV). BP also varies on a beat-to-beat basis, quantified by methods that parse variation into discrete bins, e.g., low frequency (0.04-0.15 Hz, LF). However, beat-to-beat BPV requires continuous recordings that are not easily acquired. As a result, we know little about the relationship between LF-BPV and basic sociodemographic characteristics such as age, sex, and race and clinical conditions. Methods: We computed LF-BPV during an 11-min resting period in 2,118 participants in the Midlife in the US (MIDUS) study. Results: LF-BPV was negatively associated with age, greater in men than women, and unrelated to race or socioeconomic status. It was greater in participants with hypertension but unrelated to hyperlipidemia, hypertriglyceridemia, diabetes, elevated CRP, or obesity. LF-diastolic BPV (DBPV), but not-systolic BPV (SBPV), was negatively correlated with IL-6 and s-ICAM and positively correlated with urinary epinephrine and cortisol. Finally, LF-DBPV was negatively associated with mortality, an effect was rendered nonsignificant by adjustment by age but not other sociodemographic characteristics. Discussion: These findings, the first from a large, national sample, suggest that LF-BPV differs significantly from VVV-BP and ABPV. Confirming its relationship to sociodemographic risk factors and clinical outcomes requires further study with large and representative samples.
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Affiliation(s)
- Tara Gruenewald
- Department of Psychology, Chapman University, Orange, CA, United States
| | - Teresa E. Seeman
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, United States
| | - Tse-Hwei Choo
- Mental Health Data Science Division, New York State Psychiatric Institute, New York, NY, United States
| | - Jennifer Scodes
- Mental Health Data Science Division, New York State Psychiatric Institute, New York, NY, United States
| | - Clayton Snyder
- Mental Health Data Science Division, New York State Psychiatric Institute, New York, NY, United States
| | - Martina Pavlicova
- Department of Biostatistics, Mailman School of Public Health, Columbia University Irving Medical Center, New York, NY, United States
| | | | - Joseph E. Schwartz
- Renaissance School of Medicine, Stony Brook University, New York, NY, United States
- Department of Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Ramakrishna Mukkamala
- Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Richard P. Sloan
- Division of Behavioral Medicine, Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, United States
- New York State Psychiatric Institute, New York, NY, United States
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Anderson GK, Rickards CA. The potential therapeutic benefits of low frequency haemodynamic oscillations. J Physiol 2022; 600:3905-3919. [PMID: 35883272 PMCID: PMC9444954 DOI: 10.1113/jp282605] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 07/22/2022] [Indexed: 11/08/2022] Open
Abstract
Haemodynamic oscillations occurring at frequencies below the rate of respiration have been observed experimentally for more than a century. Much of the research regarding these oscillations, observed in arterial pressure and blood flow, has focused on mechanisms of generation and methods of quantification. However, examination of the physiological role of these oscillations has been limited. Multiple studies have demonstrated that oscillations in arterial pressure and blood flow are associated with the protection in tissue oxygenation or functional capillary density during conditions of reduced tissue perfusion. There is also evidence that oscillatory blood flow can improve clearance of interstitial fluid, with a growing number of studies demonstrating a role for oscillatory blood flow to aid in clearance of debris from the brain. The therapeutic potential of these haemodynamic oscillations is an important new area of research which may have beneficial impact in treating conditions such as stroke, cardiac arrest, blood loss injuries, sepsis, or even Alzheimer's disease and vascular dementia.
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Affiliation(s)
- Garen K Anderson
- Cerebral & Cardiovascular Physiology Laboratory, Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Caroline A Rickards
- Cerebral & Cardiovascular Physiology Laboratory, Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
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4
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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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Betge S, Drinda S, Neumann T, Bäz L, Pfeil A, Schulze C, Mrowka R, Jung C, Franz M. Influence of Macitentan on the Vascular Tone and Recruitment of Finger Capillaries Under Hypobaric Hypoxia in High Altitude. High Alt Med Biol 2020; 21:336-345. [PMID: 32758029 DOI: 10.1089/ham.2019.0120] [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: 11/12/2022] Open
Abstract
Betge, Stefan, Stefan Drinda, Thomas Neumann, Laura Bäz, Alexander Pfeil, Christian Schulze, Ralf Mrowka, Christian Jung, and Marcus Franz. Influence of macitentan on the vascular tone and recruitment of finger capillaries under hypobaric hypoxia in high altitude. High Alt Med Biol. 21:336-345, 2020. Introduction: Acute normobaric (NH) and hypobaric hypoxia (HH) has effects on the vascular tone of larger arteries and may have effects on the microcirculation. These effects may be noninvasively detectable by automated devices. A part of these effects may be mediated by endothelin (ET) and should be influenced by macitentan (MAC), a dual endothelin receptor antagonist (ERA). Methods: We used photoplethysmographic sensors, fingertip volume sensors, nailfold capillaroscopy, and laser Doppler probes at rest and after a 5-minute forearm ischemia in healthy study subjects under NH, under HH, and under HH plus a single dose of MAC. Results: NH at simulated 4000 m led to increased heart rates (HR) and pulse wave velocities (PWV) and reduced augmentation index (AIX). The values for the AIX showed a high SD and differed between the used devices. At simulated 5500 m, only baseline mean value (BMV; EndoPAT) showed a further change, indicating less filled capillaries of the fingertips. HH (2978 m) increased HR, blood pressure values, and PWV. Focusing on the microcirculation of the fingertips, HH reduced the BMV and the nailfold capillary density and the postischemic capillary recruitment. MAC had no effect on the BMV, but antagonized the effects of HH on the nailfold capillaries and led to a strongly increased postischemic diameter of the arterial limbs. Concordantly, the postischemic blood flow velocity increment, measured through ultrasound Doppler, was increased at ALT+MAC. Conclusions: The BMV may be a parameter for changes of the microcirculation of the finger tips. A single dose of MAC blocked hypoxia-induced capillary rarefaction and enhanced postischemic hyperemia of the fingertips. These results indicate the importance of ET-1 for the regulation of the microcirculation under hypoxia. The German Registry of Clinical Studies (DRKS) ID: 00005459.
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Affiliation(s)
- Stefan Betge
- Clinic of Internal Medicine and Angiology, Helios Klinikum Salzgitter, Salzgitter, Germany
| | - Stefan Drinda
- Department of Rheumatology, Klinik St. Katharinental, Spital Thurgau AG, Diessenhofen, Switzerland
| | - Thomas Neumann
- Clinic of Rheumatology, Kantonsspital St. Gallen, St. Gallen, Switzerland
| | - Laura Bäz
- Division of Cardiology, Department of Internal Medicine I, University Hospital Jena, Jena, Germany
| | - Alexander Pfeil
- Division of Rheumatology, Department of Internal Medicine III, University Hospital Jena, Jena, Germany
| | - Christian Schulze
- Division of Cardiology, Department of Internal Medicine I, University Hospital Jena, Jena, Germany
| | - Ralf Mrowka
- Experimental Nephrology, Clinic of Internal Medicine III, University Hospital Jena, Friedrich Schiller University Jena, Jena, Germany
| | - Christian Jung
- Division of Cardiology, Pulmonology, and Vascular Medicine, Medical Faculty, University Duesseldorf, Duesseldorf, Germany
| | - Marcus Franz
- Division of Cardiology, Department of Internal Medicine I, University Hospital Jena, Jena, Germany
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6
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Zhang T, Liu C, Hu G, Dong H, Mu X. Synchronous vasomotion of skin microvessels at acupoints on the twelve main meridians of beagle dogs. Skin Res Technol 2020; 26:851-858. [PMID: 32557943 DOI: 10.1111/srt.12886] [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: 03/09/2020] [Accepted: 05/23/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND/PURPOSE Synchronous microvascular vasomotion was detected at acupoints in our previous human study. This present study aimed to characterize the skin microvascular vasomotion at acupoints on the twelve meridians of beagle dogs. MATERIALS AND METHODS Two acupoints were selected on each meridian and exactly located at the rosy red spots by an electrochemical color-appearing method, where the electrical resistance was measured. The skin blood flow at acupoints was recorded by laser Doppler flowmetry (LDF), and microvascular vasomotion was analyzed according to LDF waveforms. RESULTS The skin electrical resistance at acupoints was significantly lower than that at control non-acupoints. The LDF waveforms at acupoints were sinusoidal, which showed the synchronization of the microvascular vasomotion. The spectral analysis revealed that the vasomotion frequencies at acupoints on the same meridian were identical but not among different meridians, and the frequencies on the twelve main meridians displayed a constant order. CONCLUSION The skin microvascular vasomotion is synchronous at acupoints of beagle dogs and has a specific frequency along the meridian, and the electrochemical color-appearing method is a feasible strategy for the precise and visual location of acupoints. The study provides evidence for the universality of synchronous vasomotion of skin microvessels at acupoints.
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Affiliation(s)
- Tao Zhang
- Beijing Key Laboratory of Traditional Chinese Veterinary Medicine, Beijing University of Agriculture, Beijing, China
| | - Chun Liu
- Beijing Key Laboratory of Traditional Chinese Veterinary Medicine, Beijing University of Agriculture, Beijing, China
| | - Ge Hu
- Beijing Key Laboratory of Traditional Chinese Veterinary Medicine, Beijing University of Agriculture, Beijing, China
| | - Hong Dong
- Beijing Key Laboratory of Traditional Chinese Veterinary Medicine, Beijing University of Agriculture, Beijing, China
| | - Xiang Mu
- Beijing Key Laboratory of Traditional Chinese Veterinary Medicine, Beijing University of Agriculture, Beijing, China
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Aldea R, Weller RO, Wilcock DM, Carare RO, Richardson G. Cerebrovascular Smooth Muscle Cells as the Drivers of Intramural Periarterial Drainage of the Brain. Front Aging Neurosci 2019; 11:1. [PMID: 30740048 PMCID: PMC6357927 DOI: 10.3389/fnagi.2019.00001] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/07/2019] [Indexed: 12/25/2022] Open
Abstract
The human brain is the organ with the highest metabolic activity but it lacks a traditional lymphatic system responsible for clearing waste products. We have demonstrated that the basement membranes of cerebral capillaries and arteries represent the lymphatic pathways of the brain along which intramural periarterial drainage (IPAD) of soluble metabolites occurs. Failure of IPAD could explain the vascular deposition of the amyloid-beta protein as cerebral amyloid angiopathy (CAA), which is a key pathological feature of Alzheimer's disease. The underlying mechanisms of IPAD, including its motive force, have not been clarified, delaying successful therapies for CAA. Although arterial pulsations from the heart were initially considered to be the motive force for IPAD, they are not strong enough for efficient IPAD. This study aims to unravel the driving force for IPAD, by shifting the perspective of a heart-driven clearance of soluble metabolites from the brain to an intrinsic mechanism of cerebral arteries (e.g., vasomotion-driven IPAD). We test the hypothesis that the cerebrovascular smooth muscle cells, whose cycles of contraction and relaxation generate vasomotion, are the drivers of IPAD. A novel multiscale model of arteries, in which we treat the basement membrane as a fluid-filled poroelastic medium deformed by the contractile cerebrovascular smooth muscle cells, is used to test the hypothesis. The vasomotion-induced intramural flow rates suggest that vasomotion-driven IPAD is the only mechanism postulated to date capable of explaining the available experimental observations. The cerebrovascular smooth muscle cells could represent valuable drug targets for prevention and early interventions in CAA.
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Affiliation(s)
- Roxana Aldea
- Mathematical Sciences, University of Southampton, Southampton, United Kingdom
| | - Roy O Weller
- Clinical Neurosciences, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, United Kingdom
| | - Donna M Wilcock
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - Roxana O Carare
- Clinical Neurosciences, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, United Kingdom
| | - Giles Richardson
- Mathematical Sciences, University of Southampton, Southampton, United Kingdom
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Di Marco LY, Farkas E, Martin C, Venneri A, Frangi AF. Is Vasomotion in Cerebral Arteries Impaired in Alzheimer's Disease? J Alzheimers Dis 2016; 46:35-53. [PMID: 25720414 PMCID: PMC4878307 DOI: 10.3233/jad-142976] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A substantial body of evidence supports the hypothesis of a vascular component in the pathogenesis of Alzheimer’s disease (AD). Cerebral hypoperfusion and blood-brain barrier dysfunction have been indicated as key elements of this pathway. Cerebral amyloid angiopathy (CAA) is a cerebrovascular disorder, frequent in AD, characterized by the accumulation of amyloid-β (Aβ) peptide in cerebral blood vessel walls. CAA is associated with loss of vascular integrity, resulting in impaired regulation of cerebral circulation, and increased susceptibility to cerebral ischemia, microhemorrhages, and white matter damage. Vasomotion— the spontaneous rhythmic modulation of arterial diameter, typically observed in arteries/arterioles in various vascular beds including the brain— is thought to participate in tissue perfusion and oxygen delivery regulation. Vasomotion is impaired in adverse conditions such as hypoperfusion and hypoxia. The perivascular and glymphatic pathways of Aβ clearance are thought to be driven by the systolic pulse. Vasomotion produces diameter changes of comparable amplitude, however at lower rates, and could contribute to these mechanisms of Aβ clearance. In spite of potential clinical interest, studies addressing cerebral vasomotion in the context of AD/CAA are limited. This study reviews the current literature on vasomotion, and hypothesizes potential paths implicating impaired cerebral vasomotion in AD/CAA. Aβ and oxidative stress cause vascular tone dysregulation through direct effects on vascular cells, and indirect effects mediated by impaired neurovascular coupling. Vascular tone dysregulation is further aggravated by cholinergic deficit and results in depressed cerebrovascular reactivity and (possibly) impaired vasomotion, aggravating regional hypoperfusion and promoting further Aβ and oxidative stress accumulation.
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Affiliation(s)
- Luigi Yuri Di Marco
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | - Eszter Farkas
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Chris Martin
- Department of Psychology, University of Sheffield, Sheffield, UK
| | - Annalena Venneri
- Department of Neuroscience, University of Sheffield, Sheffield, UK.,IRCCS, Fondazione Ospedale S. Camillo, Venice, Italy
| | - Alejandro F Frangi
- Centre for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
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Del Pozzi AT, Miller JT, Hodges GJ. The effect of heating rate on the cutaneous vasomotion responses of forearm and leg skin in humans. Microvasc Res 2016; 105:77-84. [PMID: 26808211 DOI: 10.1016/j.mvr.2016.01.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 01/19/2016] [Accepted: 01/20/2016] [Indexed: 11/19/2022]
Abstract
We examined skin blood flow (SkBF) and vasomotion in the forearm and leg using laser-Doppler fluxmetry (LDF) and spectral analysis to investigate endothelial, sympathetic, and myogenic activities in response to slow (0.1 °C·10 s(-1)) and fast (0.5 °C·10 s(-1)) local heating. At 33 °C (thermoneutral) endothelial activity was higher in the legs than the forearms (P ≤ 0.02). Fast-heating increased SkBF more than slow heating (P=0.037 forearm; P=0.002 leg). At onset of 42 °C, endothelial (P=0.043 forearm; P=0.48 leg) activity increased in both regions during the fast-heating protocol. Following prolonged heating (42 °C) endothelial activity was higher in both the forearm (P=0.002) and leg (P<0.001) following fast-heating. These results confirm regional differences in the response to local heating and suggest that the greater increase in SkBF in response to fast local heating is initially due to increased endothelial and sympathetic activity. Furthermore, with sustained local skin heating, greater vasodilatation was observed with fast heating compared to slow heating. These data indicate that this difference is due to greater endothelial activity following fast heating compared to slow heating, suggesting that the rate of skin heating may alter the mechanisms contributing to cutaneous vasodilatation.
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Affiliation(s)
- Andrew T Del Pozzi
- Integrative Exercise Physiology Laboratory, School of Kinesiology, Ball State University, Muncie, IN 47306, United States
| | - James T Miller
- Exercise Physiology Laboratory, Department of Kinesiology, The University of Alabama, Tuscaloosa, AL 35487, United States
| | - Gary J Hodges
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada.
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10
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Park CS, Payne SJ. Modelling the effects of cerebral microvasculature morphology on oxygen transport. Med Eng Phys 2016; 38:41-7. [PMID: 26499366 PMCID: PMC4751405 DOI: 10.1016/j.medengphy.2015.09.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 07/29/2015] [Accepted: 09/10/2015] [Indexed: 12/28/2022]
Abstract
The cerebral microvasculature plays a vital role in adequately supplying blood to the brain. Determining the health of the cerebral microvasculature is important during pathological conditions, such as stroke and dementia. Recent studies have shown the complex relationship between cerebral metabolic rate and transit time distribution, the transit times of all the possible pathways available dependent on network topology. In this paper, we extend a recently developed technique to solve for residue function, the amount of tracer left in the vasculature at any time, and transit time distribution in an existing model of the cerebral microvasculature to calculate cerebral metabolism. We present the mathematical theory needed to solve for oxygen concentration followed by results of the simulations. It is found that oxygen extraction fraction, the fraction of oxygen removed from the blood in the capillary network by the tissue, and cerebral metabolic rate are dependent on both mean and heterogeneity of the transit time distribution. For changes in cerebral blood flow, a positive correlation can be observed between mean transit time and oxygen extraction fraction, and a negative correlation between mean transit time and metabolic rate of oxygen. A negative correlation can also be observed between transit time heterogeneity and the metabolic rate of oxygen for a constant cerebral blood flow. A sensitivity analysis on the mean and heterogeneity of the transit time distribution was able to quantify their respective contributions to oxygen extraction fraction and metabolic rate of oxygen. Mean transit time has a greater contribution than the heterogeneity for oxygen extraction fraction. This is found to be opposite for metabolic rate of oxygen. These results provide information on the role of the cerebral microvasculature and its effects on flow and metabolism. They thus open up the possibility of obtaining additional valuable clinical information for diagnosing and treating cerebrovascular diseases.
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Affiliation(s)
- Chang Sub Park
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, United Kingdom.
| | - Stephen J Payne
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, United Kingdom
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11
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Payne S, Oakes C, Park C. Vasomotion does inhibit mass exchange between axisymmetric blood vessels and tissue. J Theor Biol 2012; 302:1-5. [DOI: 10.1016/j.jtbi.2012.02.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Abstract
This minireview discusses vasomotion, which is the oscillation in tone of blood vessels leading to flowmotion. We will briefly discuss the prevalence of vasomotion and its potential physiological and pathophysiological relevance. We will also discuss the models that have been suggested to explain how a coordinated oscillatory activity of the smooth muscle tone can occur and emphasize the role of the endothelium, the handling of intracellular Ca(2+) and the role of smooth muscle cell ion conductances. It is concluded that vasomotion is likely to enhance tissue dialysis, although this concept still requires more experimental verification, and that an understanding at the molecular level for the pathways leading to vasomotion is beginning to emerge.
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Affiliation(s)
- C Aalkjær
- Department of Physiology and Biophysics, The Water and Salt Centre, Aarhus University, Denmark.
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