1
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Watanabe N, Iimura K, Hotta H. Ninjin'yoeito Modulates Baseline and Reperfusion-Induced Changes in the Arteriole Diameter and Blood Flow in the Cerebral Cortex of Anesthetized Mice. Microcirculation 2024:e12880. [PMID: 39120967 DOI: 10.1111/micc.12880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 07/22/2024] [Accepted: 07/26/2024] [Indexed: 08/11/2024]
Abstract
OBJECTIVE Intragastric administration of ninjin'yoeito (NYT), a traditional Japanese herbal medicine, reportedly prevents the decrease in baseline cerebral blood flow (CBF) in the cortex following gastric administration of water. We investigated the effect of NYT on baseline and dynamic changes in cerebral cortical arteriole diameter. METHODS Urethane-anesthetized mice were intragastrically administered 1 g/kg NYT or distilled water (DW). The artery in the left parietal cortex was imaged using two-photon microscopy. The baseline diameter of penetrating arterioles was measured before and 50-60 min after administration. Dynamic CBF and arteriole diameter changes before, during, and after transient occlusion of the left common carotid artery were measured approximately 10 min after administration. RESULTS DW decreased the baseline diameter of the penetrating arterioles, whereas NYT did not. During occlusion, the increase in penetrating arteriole diameter was comparable for DW and NYT; however, during reperfusion, the return to preocclusion diameter was slower for NYT than DW. Laser-speckle contrast imaging confirmed that CBF, although comparable during occlusion, was higher during reperfusion for NYT than DW. CONCLUSIONS These results suggest that NYT attenuates vasoconstriction in penetrating arterioles after intragastric administration and during cerebral reperfusion, contributing to CBF regulation.
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Affiliation(s)
- Nobuhiro Watanabe
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Kaori Iimura
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Harumi Hotta
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
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2
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Zhou Q, Glück C, Tang L, Glandorf L, Droux J, El Amki M, Wegener S, Weber B, Razansky D, Chen Z. Cortex-wide transcranial localization microscopy with fluorescently labeled red blood cells. Nat Commun 2024; 15:3526. [PMID: 38664419 PMCID: PMC11045747 DOI: 10.1038/s41467-024-47892-3] [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: 11/13/2023] [Accepted: 04/15/2024] [Indexed: 04/28/2024] Open
Abstract
Large-scale imaging of brain activity with high spatio-temporal resolution is crucial for advancing our understanding of brain function. The existing neuroimaging techniques are largely limited by restricted field of view, slow imaging speed, or otherwise do not have the adequate spatial resolution to capture brain activities on a capillary and cellular level. To address these limitations, we introduce fluorescence localization microscopy aided with sparsely-labeled red blood cells for cortex-wide morphological and functional cerebral angiography with 4.9 µm spatial resolution and 1 s temporal resolution. When combined with fluorescence calcium imaging, the proposed method enables extended recordings of stimulus-evoked neuro-vascular changes in the murine brain while providing simultaneous multiparametric readings of intracellular neuronal activity, blood flow velocity/direction/volume, and vessel diameter. Owing to its simplicity and versatility, the proposed approach will become an invaluable tool for deciphering the regulation of cortical microcirculation and neurovascular coupling in health and disease.
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Affiliation(s)
- Quanyu Zhou
- Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering, Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland
| | - Chaim Glück
- Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich, Switzerland
- Zurich Neuroscience Center, Zurich, Switzerland
| | - Lin Tang
- Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering, Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland
| | - Lukas Glandorf
- Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering, Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland
| | - Jeanne Droux
- Zurich Neuroscience Center, Zurich, Switzerland
- Department of Neurology, University Hospital and University of Zurich, Zurich, Switzerland
| | - Mohamad El Amki
- Zurich Neuroscience Center, Zurich, Switzerland
- Department of Neurology, University Hospital and University of Zurich, Zurich, Switzerland
| | - Susanne Wegener
- Zurich Neuroscience Center, Zurich, Switzerland
- Department of Neurology, University Hospital and University of Zurich, Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich, Switzerland
- Zurich Neuroscience Center, Zurich, Switzerland
| | - Daniel Razansky
- Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich, Switzerland.
- Institute for Biomedical Engineering, Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland.
- Zurich Neuroscience Center, Zurich, Switzerland.
| | - Zhenyue Chen
- Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich, Switzerland.
- Institute for Biomedical Engineering, Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland.
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3
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Westwood J, Mayhook-Walker I, Simpkins C, Darby-Smith A, Morris D, Normando E. Retinal Vascular Changes in Response to Hypoxia: A High-Altitude Expedition Study. High Alt Med Biol 2024; 25:49-59. [PMID: 38011631 DOI: 10.1089/ham.2023.0084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023] Open
Abstract
Westwood, Jessica, India Mayhook-Walker, Ciaran Simpkins, Andrew Darby-Smith, Dan Morris, and Eduardo Normando. Retinal vascular changes in response to hypoxia: a high-altitude expedition study. High Alt Med Biol. 25:49-59, 2024. Background: Increased tortuosity and engorgement of retinal vasculature are recognized physiological responses to hypoxia. This can lead to high-altitude retinopathy (HAR), but incidence reports are highly variable, and our understanding of the etiological mechanisms remains incomplete. This study quantitatively evaluated retinal vascular changes during an expedition to 4,167 m. Methods: Ten healthy participants summited Mount Toubkal, Morocco. Fundus images were taken predeparture, daily throughout the expedition, and 1 month postreturn. Diameter and tortuosity of four vessels were assessed, in addition to vessel density and features of HAR. Results: Significant (p ≤ 0.05) increases in tortuosity and diameter were observed in several vessels on high-altitude exposure days. There was a strong correlation between altitude and supratemporal retinal artery diameter on days 2, 3, and 6 of the expedition (r = 0.7707, 0.7951, 0.7401, respectively; p < 0.05). There was a significant increase in median vessel density from 6.7% at baseline to 10.0% on summit day. Notably there were no incidences of HAR. Conclusion: Physiological but not pathological changes were seen in this cohort, which gives insight into the state of the cerebral vasculature throughout this expedition. These results are likely attributable to relatively low altitude exposure, a conservative ascent profile, and the cohort's demographic. Future study must include daily retinal images at higher altitudes and take steps to mitigate environmental confounders. This study is relevant to altitude tourists, patients with diabetic retinopathy or retinal vein occlusion, and critically ill patients.
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Affiliation(s)
- Jessica Westwood
- Imperial College London Ophthalmology Research Group, Western Eye Hospital, London, United Kingdom
| | - India Mayhook-Walker
- Imperial College London Ophthalmology Research Group, Western Eye Hospital, London, United Kingdom
| | - Ciaran Simpkins
- Imperial College London Ophthalmology Research Group, Western Eye Hospital, London, United Kingdom
| | - Andrew Darby-Smith
- Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Dan Morris
- Cardiff Eye Unit, University Hospital of Wales, Cardiff, United Kingdom
| | - Eduardo Normando
- Imperial College London Ophthalmology Research Group, Western Eye Hospital, London, United Kingdom
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4
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Panahi A, Rezaee A, Hajati F, Shariflou S, Agar A, Golzan SM. Autonomous assessment of spontaneous retinal venous pulsations in fundus videos using a deep learning framework. Sci Rep 2023; 13:14445. [PMID: 37660115 PMCID: PMC10475061 DOI: 10.1038/s41598-023-41110-8] [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: 02/12/2023] [Accepted: 08/22/2023] [Indexed: 09/04/2023] Open
Abstract
The presence or absence of spontaneous retinal venous pulsations (SVP) provides clinically significant insight into the hemodynamic status of the optic nerve head. Reduced SVP amplitudes have been linked to increased intracranial pressure and glaucoma progression. Currently, monitoring for the presence or absence of SVPs is performed subjectively and is highly dependent on trained clinicians. In this study, we developed a novel end-to-end deep model, called U3D-Net, to objectively classify SVPs as present or absent based on retinal fundus videos. The U3D-Net architecture consists of two distinct modules: an optic disc localizer and a classifier. First, a fast attention recurrent residual U-Net model is applied as the optic disc localizer. Then, the localized optic discs are passed on to a deep convolutional network for SVP classification. We trained and tested various time-series classifiers including 3D Inception, 3D Dense-ResNet, 3D ResNet, Long-term Recurrent Convolutional Network, and ConvLSTM. The optic disc localizer achieved a dice score of 95% for locating the optic disc in 30 milliseconds. Amongst the different tested models, the 3D Inception model achieved an accuracy, sensitivity, and F1-Score of 84 ± 5%, 90 ± 8%, and 81 ± 6% respectively, outperforming the other tested models in classifying SVPs. To the best of our knowledge, this research is the first study that utilizes a deep neural network for an autonomous and objective classification of SVPs using retinal fundus videos.
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Affiliation(s)
- Amirhossein Panahi
- Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran
| | - Alireza Rezaee
- Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran.
| | - Farshid Hajati
- Intelligent Technology Innovation Lab (ITIL) Group, Institute for Sustainable Industries and Liveable Cities, Victoria University, Footscray, Australia
| | - Sahar Shariflou
- Vision Science Group, Graduate School of Health, University of Technology Sydney, Ultimo, Australia
| | - Ashish Agar
- Ophthalmology Department, Prince of Wales Hospital, Sydney, NSW, Australia
- Department of Ophthalmology, University of New South Wales, Sydney, NSW, Australia
- Marsden Eye Specialists, Sydney, NSW, Australia
| | - S Mojtaba Golzan
- Vision Science Group, Graduate School of Health, University of Technology Sydney, Ultimo, Australia
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5
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Solari E, Marcozzi C, Negrini D, Moriondo A. Fluid Osmolarity Modulates the Rate of Spontaneous Contraction of Lymphatic Vessels and Lymph Flow by Means of a Cooperation between TRPV and VRAC Channels. BIOLOGY 2023; 12:1039. [PMID: 37508468 PMCID: PMC10376700 DOI: 10.3390/biology12071039] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/13/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023]
Abstract
Lymphatic vessels are capable of sustaining lymph formation and propulsion via an intrinsic mechanism based on the spontaneous contraction of the lymphatic muscle in the wall of lymphatic collectors. Exposure to a hyper- or hypo-osmolar environment can deeply affect the intrinsic contraction rate and therefore alter lymph flow. In this work, we aimed at defining the putative receptors underlying such a response. Functional experiments were conducted in ex vivo rat diaphragmatic specimens containing spontaneously contracting lymphatic vessels that were exposed to either hyper- or hypo-osmolar solutions. Lymphatics were challenged with blockers to TRPV4, TRPV1, and VRAC channels, known to respond to changes in osmolarity and/or cell swelling and expressed by lymphatic vessels. Results show that the normal response to a hyperosmolar environment is a steady decrease in the contraction rate and lymph flow and can be prevented by blocking TRPV1 channels with capsazepine. The response to a hyposmolar environment consists of an early phase of an increase in the contraction rate, followed by a decrease. The early phase is abolished by blocking VRACs with DCPIB, while blocking TRPV4 mainly resulted in a delay of the early response. Overall, our data suggest that the cooperation of the three channels can shape the response of lymphatic vessels in terms of contraction frequency and lymph flow, with a prominent role of TRPV1 and VRACs.
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Affiliation(s)
- Eleonora Solari
- Department of Medicine and Technological Innovation (DIMIT), Università degli Studi dell'Insubria, 21100 Varese, Italy
| | - Cristiana Marcozzi
- Department of Medicine and Technological Innovation (DIMIT), Università degli Studi dell'Insubria, 21100 Varese, Italy
| | - Daniela Negrini
- Department of Medicine and Technological Innovation (DIMIT), Università degli Studi dell'Insubria, 21100 Varese, Italy
| | - Andrea Moriondo
- Department of Medicine and Technological Innovation (DIMIT), Università degli Studi dell'Insubria, 21100 Varese, Italy
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6
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Phan TX, Sahibzada N, Ahern GP. Arteries are finely tuned thermosensors regulating myogenic tone and blood flow. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.22.532099. [PMID: 36993664 PMCID: PMC10055355 DOI: 10.1101/2023.03.22.532099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In response to changing blood pressure, arteries adjust their caliber to control perfusion. This vital autoregulatory property, termed vascular myogenic tone, stabilizes downstream capillary pressure. We discovered that tissue temperature critically determines myogenic tone. Heating steeply activates tone in skeletal muscle, gut, brain and skin arteries with temperature coefficients ( Q 10 ) of ∼11-20. Further, arterial thermosensitivity is tuned to resting tissue temperatures, making myogenic tone sensitive to small thermal fluctuations. Interestingly, temperature and intraluminal pressure are sensed largely independently and integrated to trigger myogenic tone. We show that TRPV1 and TRPM4 mediate heat-induced tone in skeletal muscle arteries. Variations in tissue temperature are known to alter vascular conductance; remarkably, thermosensitive tone counterbalances this effect, thus protecting capillary integrity and fluid balance. In conclusion, thermosensitive myogenic tone is a fundamental homeostatic mechanism regulating tissue perfusion. One-Sentence Summary Arterial blood pressure and temperature are integrated via thermosensitve ion channels to produce myogenic tone.
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7
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Hensel O, Burow P, Kraya T, Stoevesandt D, Naegel S. Vertebrobasilar artery elongation in migraine-a retrospective cross-sectional study. Acta Neurol Belg 2023; 123:441-450. [PMID: 35906498 PMCID: PMC10133057 DOI: 10.1007/s13760-022-02039-3] [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: 05/27/2022] [Accepted: 07/14/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND Numerous but inconclusive findings have sparked an ongoing debate about whether the arteries of migraine patients undergo vascular alterations. The outlet angle of the superior cerebellar artery (SUCA) and the lateral displacement of basilar arteries are good surrogate parameters for determining elongation of the vertebrobasilar arteries. METHODS We retrospectively determined the SUCA outlet angle and the lateral displacement of the basilar artery in 63 patients with migraine (30.6 ± 8.9 years, 84% women, 16% chronic migraine, 60% migraine with aura) and compared these with 126 age- and sex-matched control subjects. RESULTS In patients with migraine, the SUCA outlet angle was lower (159 ± 26° vs. 169 ± 29°, p = 0.020) and the lateral displacement of the basilar artery was greater (3.7 ± 2.7 mm vs. 2.8 ± 2.4 mm, p = 0.020) than in the control subjects. Age, gender, migraine characteristics and presence of any cardiovascular risk factors did not affect the SUCA outlet angle or lateral displacement of the basilar artery. CONCLUSION Migraine patients exhibited a lower SUCA outlet angle and greater lateral displacement of the basilar arteries. Both may be attributable to the elongation of the vertebrobasilar arteries, which is an indication of arterial wall pathology in migraine.
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Affiliation(s)
- Ole Hensel
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, University Hospital Halle, Halle (Saale), Germany.
| | - Philipp Burow
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, University Hospital Halle, Halle (Saale), Germany
| | - Torsten Kraya
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, University Hospital Halle, Halle (Saale), Germany
- Department of Neurology, St. Georg Hospital Leipzig, Leipzig, Germany
| | - Dietrich Stoevesandt
- Department of Radiology, Martin-Luther-University Halle-Wittenberg, University Hospital Halle, Halle (Saale), Germany
| | - Steffen Naegel
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, University Hospital Halle, Halle (Saale), Germany
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8
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Yu J, Zhu H, Kindy MS, Taheri S. The impact of a high-sodium diet regimen on cerebrovascular morphology and cerebral perfusion in Alzheimer's disease. CEREBRAL CIRCULATION - COGNITION AND BEHAVIOR 2023; 4:100161. [PMID: 36741272 PMCID: PMC9895990 DOI: 10.1016/j.cccb.2023.100161] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 12/05/2022] [Accepted: 01/27/2023] [Indexed: 01/30/2023]
Abstract
Introduction Various lifestyle factors such as chronic hypertension and a high-sodium diet regimen are shown to impact cerebrovascular morphology and structure. Unusual cerebrovascular morphological and structural changes may contribute to cerebral hypoperfusion in Alzheimer's disease (AD). The objective of this study was to examine whether a high-sodium diet mediates cerebrovascular morphology and cerebral perfusion alterations in AD. Methods Double transgenic mice harboring Aβ precursor protein (APPswe) and presenilin-1 (PSEN1) along with wild-type controls were divided into four groups. Group A (APP/PS1) and B (controls) were both fed a high-sodium (4.00%), while group C (APP/PS1) and D (controls) were both fed a low-sodium (0.08% a regular chow diet) for three months. Then, changes in regional cerebral perfusion and diffusion, cerebrovascular morphology, and structure were quantified. Results A 3-month high-sodium diet causes pyknosis and deep staining in hippocampal neurons and reduced vascular density in both hippocampal and cortical areas (p <0.001) of APP/PS1. Despite vascular density changes, cerebral perfusion was not increased markedly (p = 0.3) in this group, though it was increased more in wild-type controls (p = 0.022). Conclusion A high-sodium diet regimen causes cerebrovascular morphology alteration in APP/PS1 mouse model of AD.
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Affiliation(s)
- Jin Yu
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL 33612, USA
| | - Hong Zhu
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL 33612, USA
| | - Mark S. Kindy
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL 33612, USA,James A. Haley VA Medical Center, Tampa, FL 33612, USA
| | - Saeid Taheri
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL 33612, USA,USF Heart Institute, Tampa, FL 33612, USA,Corresponding author at: Department of Pharmaceutical Sciences, USF Heart Institute, University of South Florida, 12901 Bruce B. Downs Blvd., MDC 30, Tampa, FL 33612, USA.
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9
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Oghifobibi OA, Toader AE, Nicholas MA, Nelson BP, Alindogan NG, Wolf MS, Kline AE, Nouraie SM, Bondi CO, Iordanova B, Clark RS, Bayır H, Loughran PA, Watkins SC, St Croix CM, Kochanek PM, Vazquez AL, Manole MD. Resuscitation with epinephrine worsens cerebral capillary no-reflow after experimental pediatric cardiac arrest: An in vivo multiphoton microscopy evaluation. J Cereb Blood Flow Metab 2022; 42:2255-2269. [PMID: 35854408 PMCID: PMC9670003 DOI: 10.1177/0271678x221113022] [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: 01/21/2023]
Abstract
Epinephrine is the principal resuscitation therapy for pediatric cardiac arrest (CA). Clinical data suggest that although epinephrine increases the rate of resuscitation, it fails to improve neurological outcome, possibly secondary to reductions in microvascular flow. We characterized the effect of epinephrine vs. placebo administered at resuscitation from pediatric asphyxial CA on microvascular and macrovascular cortical perfusion assessed using in vivo multiphoton microscopy and laser speckle flowmetry, respectively, and on brain tissue oxygenation (PbO2), behavioral outcomes, and neuropathology in 16-18-day-old rats. Epinephrine-treated rats had a more rapid return of spontaneous circulation and brisk immediate cortical reperfusion during 1-3 min post-CA vs. placebo. However, at the microvascular level, epinephrine-treated rats had penetrating arteriole constriction and increases in both capillary stalling (no-reflow) and cortical capillary transit time 30-60 min post-CA vs. placebo. Placebo-treated rats had increased capillary diameters post-CA. The cortex was hypoxic post-CA in both groups. Epinephrine treatment worsened reference memory performance vs. shams. Hippocampal neuron counts did not differ between groups. Resuscitation with epinephrine enhanced immediate reperfusion but produced microvascular alterations during the first hour post-resuscitation, characterized by vasoconstriction, capillary stasis, prolonged cortical transit time, and absence of compensatory cortical vasodilation. Targeted therapies mitigating the deleterious microvascular effects of epinephrine are needed.
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Affiliation(s)
- Onome A Oghifobibi
- Department of Pediatrics, University of Pittsburgh, Pittsburgh, USA.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA
| | - Andrew E Toader
- Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, USA
| | - Melissa A Nicholas
- Department of Pediatrics, University of Pittsburgh, Pittsburgh, USA.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA
| | - Brittany P Nelson
- Department of Pediatrics, University of Pittsburgh, Pittsburgh, USA.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA
| | - Nicole G Alindogan
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA
| | - Michael S Wolf
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA.,Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, USA
| | - Anthony E Kline
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA.,Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, USA
| | - Seyed M Nouraie
- Department of Medicine, University of Pittsburgh, Pittsburgh, USA
| | - Corina O Bondi
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA.,Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, USA
| | - Bistra Iordanova
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, USA
| | - Robert Sb Clark
- Department of Pediatrics, University of Pittsburgh, Pittsburgh, USA.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA.,Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, USA.,Children's Neuroscience Institute, UPMC Children's Hospital, Pittsburgh, USA
| | - Hülya Bayır
- Department of Pediatrics, University of Pittsburgh, Pittsburgh, USA.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA.,Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, USA.,Children's Neuroscience Institute, UPMC Children's Hospital, Pittsburgh, USA
| | | | - Simon C Watkins
- Department of Cell Biology, Center for Biologic Imaging University of Pittsburgh, Pittsburgh, USA
| | - Claudette M St Croix
- Department of Cell Biology, Center for Biologic Imaging University of Pittsburgh, Pittsburgh, USA
| | - Patrick M Kochanek
- Department of Pediatrics, University of Pittsburgh, Pittsburgh, USA.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA.,Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, USA.,Children's Neuroscience Institute, UPMC Children's Hospital, Pittsburgh, USA
| | - Alberto L Vazquez
- Department of Radiology, University of Pittsburgh, Pittsburgh, USA.,Department of Bioengineering, University of Pittsburgh, Pittsburgh, USA
| | - Mioara D Manole
- Department of Pediatrics, University of Pittsburgh, Pittsburgh, USA.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA.,Children's Neuroscience Institute, UPMC Children's Hospital, Pittsburgh, USA
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10
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Döring K, Sperling S, Ninkovic M, Schroeder H, Fischer A, Stadelmann C, Streit F, Binder L, Mielke D, Rohde V, Malinova V. Ultrasound-Induced Release of Nimodipine from Drug-Loaded Block Copolymer Micelles: In Vivo Analysis. Transl Stroke Res 2022; 13:792-800. [PMID: 34988870 PMCID: PMC9391244 DOI: 10.1007/s12975-021-00979-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 12/01/2021] [Accepted: 12/14/2021] [Indexed: 12/03/2022]
Abstract
Nimodipine prevents cerebral vasospasm and improves functional outcome after aneurysmal subarachnoid hemorrhage (aSAH). The beneficial effect is limited by low oral bioavailability of nimodipine, which resulted in an increasing use of nanocarriers with sustained intrathecal drug release in order to overcome this limitation. However, this approach facilitates only a continuous and not an on-demand nimodipine release during the peak time of vasospasm development. In this study, we aimed to assess the concept of controlled drug release from nimodipine-loaded copolymers by ultrasound application in the chicken chorioallantoic membrane (CAM) model. Nimodipine-loaded copolymers were produced with the direct dissolution method. Vasospasm of the CAM vessels was induced by means of ultrasound (Physiomed, continuous wave, 3 MHz, 1.0 W/cm2). The ultrasound-mediated nimodipine release (Physiomed, continuous wave, 1 MHz, 1.7 W/cm2) and its effect on the CAM vessels were evaluated. Measurements of vessel diameter before and after ultrasound-induced nimodipine release were performed using ImageJ. The CAM model could be successfully carried out in all 25 eggs. After vasospasm induction and before drug release, the mean vessel diameter was at 57% (range 44-61%) compared to the baseline diameter (set at 100%). After ultrasound-induced drug release, the mean vessel diameter of spastic vessels increased again to 89% (range 83-91%) of their baseline diameter, which was significant (p = 0.0002). We were able to provide a proof of concept for in vivo vasospasm induction by ultrasound application in the CAM model and subsequent resolution by ultrasound-mediated nimodipine release from nanocarriers. This concept merits further evaluation in a rat SAH model.
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Affiliation(s)
- Katja Döring
- Department of Neurosurgery, University Medical Center Göttingen, Göttingen, Germany
- Department of Neuroradiology, University Medical Center Göttingen, Göttingen, Germany
| | - Swetlana Sperling
- Department of Neurosurgery, University Medical Center Göttingen, Göttingen, Germany
| | - Milena Ninkovic
- Department of Neurosurgery, University Medical Center Göttingen, Göttingen, Germany
| | - Henning Schroeder
- Department for Epigenetics and System Medicine in Neurodegenerative Diseases, German Center for Neurodegenerative Diseases, Göttingen, Germany
| | - André Fischer
- Department for Epigenetics and System Medicine in Neurodegenerative Diseases, German Center for Neurodegenerative Diseases, Göttingen, Germany
| | - Christine Stadelmann
- Department of Neuropathology, University Medical Center Göttingen, Göttingen, Germany
| | - Frank Streit
- Institute for Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Lutz Binder
- Institute for Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Dorothee Mielke
- Department of Neurosurgery, University Medical Center Göttingen, Göttingen, Germany
| | - Veit Rohde
- Department of Neurosurgery, University Medical Center Göttingen, Göttingen, Germany
| | - Vesna Malinova
- Department of Neurosurgery, University Medical Center Göttingen, Göttingen, Germany.
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11
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Photoacoustic imaging for in vivo quantification of alcohol-induced structural and functional changes in cerebral vasculature in high alcohol-preferring mice (HAP). Alcohol 2022; 100:23-30. [PMID: 35085740 PMCID: PMC9906794 DOI: 10.1016/j.alcohol.2022.01.001] [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: 02/15/2021] [Revised: 01/03/2022] [Accepted: 01/04/2022] [Indexed: 11/23/2022]
Abstract
Alcohol-induced structural and functional changes were studied in vivo by photoacoustic tomography (PAT) of the cerebrovascular system in selectively bred alcohol-preferring mice. High (HAP) and low (LAP) alcohol-preferring mice are replicate lines of mice selectively bred to prefer 10% (v/v) ethanol to water and water to ethanol, respectively, in a free-access two-bottle choice scenario. A cohort of 15 singly-housed alcohol-preferring mice (five HAP mice for the experimental group, five LAP mice for the control group, and five other LAP mice set aside) were given free-access two-bottle choice 10% ethanol (v/v) and water in 50-mL graduated drinking bottles mounted on each of their cages for 4 weeks prior to PAT brain scanning. A daily log of the volume of ethanol consumed over a 24-h period was kept. At the end of the fourth week, blood samples were collected from the HAP mice and blood ethanol concentrations (BECs) were measured to ascertain their levels of ethanol intoxication. The mice were then grouped into five weight-matched pairs of HAP and LAP for comparison purposes, and noninvasive in vivo PAT imaging was performed on each weight-matched pair. To mimic a binge drinking paradigm, mice were rearranged into four weight-matched groups of three animals each: an HAP mouse and two LAP mice. For each group, one HAP mouse and one LAP mouse received a 20% ethanol solution via intraperitoneal (i.p.) injection after 24 h of ethanol abstinence, in weight-based doses of 3 g/kg prior to imaging, while the last LAP mouse received a sham i.p. injection. PAT images of the brain were collected for 30 min thereafter. Cerebral vascular diameters for selected vessels of interest were extracted from the PAT images and compared between HAP mice and LAP mice. For the binge scenario, changes in vessel diameter and hemoglobin oxygen saturation were extracted from PAT images and studied over a 30-min duration. Vascular diameter was significantly smaller in HAP mice compared to LAP mice in weight-matched pairs. Hemoglobin-oxygen saturation and vessel diameter dropped more quickly in LAP mice than in HAP mice following a 20% ethanol i.p. injection (3 g/kg), with a 32% reduction in cerebrovascular diameter in a 30-min period. This study demonstrates the effectiveness of PAT in alcohol addiction imaging and diagnosis, and its feasibility in studying alcohol-induced changes in vascular structure and perfusion. It also adds to other bodies of evidence to suggest that the effects of binge drinking are more adverse in occasional drinkers than habitual drinkers.
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In Vivo Vasospasm Induction by Ultrasound Application in the Chicken Chorioallantoic Membrane Model. Transl Stroke Res 2022; 13:616-624. [PMID: 35061211 PMCID: PMC9232457 DOI: 10.1007/s12975-021-00960-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 10/01/2021] [Accepted: 10/26/2021] [Indexed: 11/29/2022]
Abstract
Cerebral vasospasm is a highly investigated phenomenon in neurovascular research. Experimental vasospasm models are irreplaceable for the evaluation of new antivasospastic drugs. In this study, we assessed the reliability of in vivo vasospasm induction by ultrasound application in the chicken chorioallantoic membrane (CAM) model. After incubation of fertilized chicken eggs for four days, a fenestration was performed to enable examination of the CAM vessels. On the thirteenth day, continuous-wave ultrasound (3 MHz, 1 W/cm2) was applied on the CAM vessels for 60 s. The ultrasound effect on the vessels was recorded by life imaging (5-MP HD-microscope camera, Leica®). The induced vessel diameter changes were evaluated in a defined time interval of 20 min using a Fiji macro. The vessel diameter before and after sonication was measured and the relative diameter reduction was determined. A first reduction of vessel diameter was observed after three minutes with an average vessel-diameter decrease to 77%. The maximum reduction in vessel diameter was reached eight minutes after sonication with an average vessel diameter decrease to 57% (mean relative diameter reduction of 43%, range 44–61%), ANOVA, p = 0.0002. The vasospasm persisted for all 20 recorded minutes post induction. Vasospasm can be reliably induced by short application of 3 MHz-ultrasound to the CAM vessels. This might be a suitable in vivo model for the evaluation of drug effects on vasospasm in an experimental setting as intermediary in the transition process from in vitro to in vivo assessment using animal models.
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13
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Phan TX, Ton HT, Gulyás H, Pórszász R, Tóth A, Russo R, Kay MW, Sahibzada N, Ahern GP. TRPV1 in arteries enables a rapid myogenic tone. J Physiol 2022; 600:1651-1666. [PMID: 35020949 PMCID: PMC8976781 DOI: 10.1113/jp281873] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 01/11/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS We explored the physiological role of TRPV1 in vascular smooth muscle. TRPV1 antagonists dilated skeletal muscle arterioles both ex vivo and in vivo, increased coronary perfusion and decreased systemic blood pressure. Stretch of arteriolar myocytes and increases in intraluminal pressure in arteries triggered rapid Ca2+ signaling and vasoconstriction respectively. Pharmacologic and/or genetic disruption of TRPV1 significantly inhibited the magnitude and rate of these responses. Furthermore, disrupting TRPV1 blunted the rapid vasodilation evoked by arterial constriction. Pharmacological experiments identified key roles for phospholipase C and protein kinase C, combined with temperature, in TRPV1-dependent arterial tone. These results show that TRPV1 in arteriolar myocytes dynamically regulates myogenic tone and blood flow in the heart and skeletal muscle. ABSTRACT Arterioles maintain blow flow by adjusting their diameter in response to changes in local blood pressure. In this process called the myogenic response, a vascular smooth muscle mechanosensor controls tone predominantly through altering the membrane potential. In general, myogenic responses occur slowly (minutes). In the heart and skeletal muscle, however, tone is activated rapidly (tens of seconds) and terminated by brief (100 ms) arterial constrictions. Previously, we identified extensive expression of TRPV1 in the smooth muscle of arterioles supplying skeletal muscle, heart and fat. Here we reveal a critical role for TRPV1 in the rapid myogenic tone of these tissues. TRPV1 antagonists dilated skeletal muscle arterioles in vitro and in vivo, increased coronary flow in isolated hearts, and transiently decreased blood pressure. All of these pharmacologic effects were abolished by genetic disruption of TRPV1. Stretch of isolated vascular smooth muscle cells or raised intravascular pressure in arteries triggered Ca2+ signaling and vasoconstriction. The majority of these stretch-responses were TRPV1-mediated, with the remaining tone being inhibited by the TRPM4 antagonist, 9-phenantrol. Notably, tone developed more quickly in arteries from wild-type compared with TRPV1-null mice. Furthermore, the immediate vasodilation following brief constriction of arterioles depended on TRPV1, consistent with a rapid deactivation of TRPV1. Pharmacologic experiments revealed that membrane stretch activates phospholipase C/protein kinase C signaling combined with heat to activate TRPV1, and in turn, L-type Ca2+ channels. These results suggest a critical role, for TRPV1 in the dynamic regulation of myogenic tone and blood flow in the heart and skeletal muscle. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Thieu X Phan
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA.,Department of Biology, Vinh University, Vinh City, Vietnam
| | - Hoai T Ton
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA.,Department of Biology, Vinh University, Vinh City, Vietnam
| | - Hajnalka Gulyás
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Debrecen, Doctoral School of Pharmaceutical Sciences, Debrecen, Hungary
| | - Róbert Pórszász
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Debrecen, Doctoral School of Pharmaceutical Sciences, Debrecen, Hungary
| | - Attila Tóth
- Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Rebekah Russo
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Matthew W Kay
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Niaz Sahibzada
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA
| | - Gerard P Ahern
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA
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14
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Risch M, Vogler B, Dux M, Messlinger K. CGRP outflow into jugular blood and cerebrospinal fluid and permeance for CGRP of rat dura mater. J Headache Pain 2021; 22:105. [PMID: 34496764 PMCID: PMC8424805 DOI: 10.1186/s10194-021-01320-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 08/31/2021] [Indexed: 12/11/2022] Open
Abstract
Background Calcitonin gene-related peptide (CGRP) is released from activated meningeal afferent fibres in the cranial dura mater, which likely accompanies severe headache attacks. Increased CGRP levels have been observed in different extracellular fluid compartments during primary headaches such as migraine but it is not entirely clear how CGRP is drained from the meninges. Methods We have used an in vivo preparation of the rat to examine after which time and at which concentration CGRP applied onto the exposed parietal dura mater appears in the jugular venous blood and the cerebrospinal fluid (CSF) collected from the cisterna magna. Recordings of meningeal (dural) and cortical (pial) blood flow were used to monitor the vasodilatory effect of CGRP. In a new ex vivo preparation we examined how much of a defined CGRP concentration applied to the arachnoidal side penetrates the dura. CGRP concentrations were determined with an approved enzyme immunoassay. Results CGRP levels in the jugular plasma in vivo were slightly elevated compared to baseline values 5-20 min after dural application of CGRP (10 μM), in the CSF a significant three-fold increase was seen after 35 min. Meningeal but not cortical blood flow showed significant increases. The spontaneous CGRP release from the dura mater ex vivo was above the applied low concentration of 1 pM. CGRP at 1 nM did only partly penetrate the dura. Conclusions We conclude that only a small fraction of CGRP applied onto the dura mater reaches the jugular blood and, in a delayed manner, also the CSF. The dura mater may constitute a barrier for CGRP and limits diffusion into the CSF of the subarachnoidal space, where the CGRP concentration is too low to cause vasodilatation.
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Affiliation(s)
- Miriam Risch
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University Erlangen-Nürnberg, Universitätsstr. 17, D-91054, Erlangen, Germany
| | - Birgit Vogler
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University Erlangen-Nürnberg, Universitätsstr. 17, D-91054, Erlangen, Germany
| | - Mária Dux
- Department of Physiology, University of Szeged, Dóm tér 10, Szeged, H-6720, Hungary
| | - Karl Messlinger
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University Erlangen-Nürnberg, Universitätsstr. 17, D-91054, Erlangen, Germany.
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15
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Wu JW, Jung Y, Yeh SCA, Seo Y, Runnels JM, Burns CS, Mizoguchi T, Ito K, Spencer JA, Lin CP. Intravital fluorescence microscopy with negative contrast. PLoS One 2021; 16:e0255204. [PMID: 34351959 PMCID: PMC8341626 DOI: 10.1371/journal.pone.0255204] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 07/13/2021] [Indexed: 11/23/2022] Open
Abstract
Advances in intravital microscopy (IVM) have enabled the studies of cellular organization and dynamics in the native microenvironment of intact organisms with minimal perturbation. The abilities to track specific cell populations and monitor their interactions have opened up new horizons for visualizing cell biology in vivo, yet the success of standard fluorescence cell labeling approaches for IVM comes with a "dark side" in that unlabeled cells are invisible, leaving labeled cells or structures to appear isolated in space, devoid of their surroundings and lacking proper biological context. Here we describe a novel method for "filling in the void" by harnessing the ubiquity of extracellular (interstitial) fluid and its ease of fluorescence labelling by commonly used vascular and lymphatic tracers. We show that during routine labeling of the vasculature and lymphatics for IVM, commonly used fluorescent tracers readily perfuse the interstitial spaces of the bone marrow (BM) and the lymph node (LN), outlining the unlabeled cells and forming negative contrast images that complement standard (positive) cell labeling approaches. The method is simple yet powerful, offering a comprehensive view of the cellular landscape such as cell density and spatial distribution, as well as dynamic processes such as cell motility and transmigration across the vascular endothelium. The extracellular localization of the dye and the interstitial flow provide favorable conditions for prolonged Intravital time lapse imaging with minimal toxicity and photobleaching.
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Affiliation(s)
- Juwell W. Wu
- Center for Systems Biology and Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yookyung Jung
- Center for Systems Biology and Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Seoul, Republic of Korea
| | - Shu-Chi A. Yeh
- Center for Systems Biology and Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yongwan Seo
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Judith M. Runnels
- Center for Systems Biology and Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Christian S. Burns
- Department of Bioengineering, University of California Merced, Merced, California, United States of America
- NSF-CREST Center for Cellular and Biomolecular Machines and the Health Science Research Institute, University of California Merced, Merced, California, United States of America
| | - Toshihide Mizoguchi
- Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, Departments of Cell Biology and Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Oral Health Science Center, Tokyo Dental College, Tokyo, Japan
| | - Keisuke Ito
- Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, Departments of Cell Biology and Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Joel A. Spencer
- Department of Bioengineering, University of California Merced, Merced, California, United States of America
- NSF-CREST Center for Cellular and Biomolecular Machines and the Health Science Research Institute, University of California Merced, Merced, California, United States of America
| | - Charles P. Lin
- Center for Systems Biology and Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
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Glück C, Ferrari KD, Binini N, Keller A, Saab AS, Stobart JL, Weber B. Distinct signatures of calcium activity in brain mural cells. eLife 2021; 10:e70591. [PMID: 34227466 PMCID: PMC8294852 DOI: 10.7554/elife.70591] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 06/15/2021] [Indexed: 12/15/2022] Open
Abstract
Pericytes have been implicated in various neuropathologies, yet little is known about their function and signaling pathways in health. Here, we characterized calcium dynamics of cortical mural cells in anesthetized or awake Pdgfrb-CreERT2;Rosa26< LSL-GCaMP6s > mice and in acute brain slices. Smooth muscle cells (SMCs) and ensheathing pericytes (EPs), also named as terminal vascular SMCs, revealed similar calcium dynamics in vivo. In contrast, calcium signals in capillary pericytes (CPs) were irregular, higher in frequency, and occurred in cellular microdomains. In the absence of the vessel constricting agent U46619 in acute slices, SMCs and EPs revealed only sparse calcium signals, whereas CPs retained their spontaneous calcium activity. Interestingly, chemogenetic activation of neurons in vivo and acute elevations of extracellular potassium in brain slices strongly decreased calcium activity in CPs. We propose that neuronal activation and an extracellular increase in potassium suppress calcium activity in CPs, likely mediated by Kir2.2 and KATP channels.
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Affiliation(s)
- Chaim Glück
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
| | - Kim David Ferrari
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
| | - Noemi Binini
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
| | - Annika Keller
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
- Department of Neurosurgery, University of ZurichSchlierenSwitzerland
| | - Aiman S Saab
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
| | - Jillian L Stobart
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Rady Faculty of Health Sciences, College of PharmacyWinnipegCanada
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
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17
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Dehghani C, Frost S, Jayasena R, Fowler C, Masters CL, Kanagasingam Y, Jiao H, Lim JKH, Chinnery HR, Downie LE. Morphometric Changes to Corneal Dendritic Cells in Individuals With Mild Cognitive Impairment. Front Neurosci 2020; 14:556137. [PMID: 33362451 PMCID: PMC7755610 DOI: 10.3389/fnins.2020.556137] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 11/09/2020] [Indexed: 11/13/2022] Open
Abstract
Purpose There has been increasing interest in identifying non-invasive, imaging biomarkers for neurodegenerative disorders of the central nervous system (CNS). The aim of this proof-of-concept study was to investigate whether corneal sensory nerve and dendritic cell (DC) parameters, captured using in vivo confocal microscopy (IVCM), are altered in individuals with mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Methods Fifteen participants were recruited from the Australian Imaging Biomarkers and Lifestyle (AIBL) study in Melbourne, VIC, Australia. The cohort consisted of cognitively normal (CN) individuals (n = 5), and those with MCI (n = 5) and AD (n = 5). Participants underwent a slit lamp examination of the anterior segment, followed by corneal imaging using laser-scanning in vivo confocal microscopy (IVCM) of the central and inferior whorl regions. Corneal DC density, field area, perimeter, circularity index, aspect ratio, and roundness were quantified using Image J. Quantitative data were derived for corneal nerve parameters, including nerve fiber length (CNFL), fiber density (CNFD), branch density (CNBD), and diameter. Results Corneal DC field area and perimeter were greater in individuals with MCI, relative to CN controls, in both the central and inferior whorl regions (p < 0.05 for all comparisons). In addition, corneal DCs in the whorl region of MCI eyes had lower circularity and roundness indices and a higher aspect ratio relative to CNs (p < 0.05 for all comparisons). DC density was similar across participant groups in both corneal regions. There was a trend toward lower quantitative parameters for corneal nerve architecture in the AD and MCI groups compared with CN participants, however, the inter-group differences did not reach statistical significance. Central corneal nerve diameters were similar between groups. Conclusion This study is the first to report morphological differences in corneal DCs in humans with MCI. These differences were evident in both the central and mid-peripheral cornea, and in the absence of significant nerve abnormalities or a difference in DC density. These findings justify future large-scale studies to assess the utility of corneal IVCM and DC analysis for identifying early stage pathology in neurodegenerative disorders of the CNS.
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Affiliation(s)
- Cirous Dehghani
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia.,CSIRO, Australian e-Health Research Centre (AEHRC), Parkville, VIC, Australia.,Discipline of Optometry, University of Canberra, Canberra, ACT, Australia
| | - Shaun Frost
- CSIRO, Australian e-Health Research Centre (AEHRC), Floreat, WA, Australia
| | - Rajiv Jayasena
- CSIRO, Australian e-Health Research Centre (AEHRC), Parkville, VIC, Australia
| | - Christopher Fowler
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Colin L Masters
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | | | - Haihan Jiao
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Jeremiah K H Lim
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia.,Optometry and Vision Science, College of Nursing and Health Sciences, Flinders University, Adelaide, SA, Australia
| | - Holly R Chinnery
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Laura E Downie
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia
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18
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Intact in vivo visualization of telencephalic microvasculature in medaka using optical coherence tomography. Sci Rep 2020; 10:19831. [PMID: 33199719 PMCID: PMC7669881 DOI: 10.1038/s41598-020-76468-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 10/28/2020] [Indexed: 11/09/2022] Open
Abstract
To date, various human disease models in small fish-such as medaka (Oryzias lapties)-have been developed for medical and pharmacological studies. Although genetic and environmental homogeneities exist, disease progressions can show large individual differences in animal models. In this study, we established an intact in vivo angiographic approach and explored vascular networks in the telencephalon of wild-type adult medaka using the spectral-domain optical coherence tomography. Our approach, which required neither surgical operations nor labeling agents, allowed to visualize blood vessels in medaka telencephala as small as about 8 µm, that is, almost the size of the blood cells of medaka. Besides, we could show the three-dimensional microvascular distribution in the medaka telencephalon. Therefore, the intact in vivo imaging via optical coherence tomography can be used to perform follow-up studies on cerebrovascular alterations in metabolic syndrome and their associations with neurodegenerative disease models in medaka.
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19
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Wong VHY, Zhao D, Bui BV, Millar CJ, Nguyen CTO. Increased episcleral venous pressure in a mouse model of circumlimbal suture induced ocular hypertension. Exp Eye Res 2020; 202:108348. [PMID: 33166503 DOI: 10.1016/j.exer.2020.108348] [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] [Received: 05/02/2020] [Revised: 10/29/2020] [Accepted: 11/03/2020] [Indexed: 11/30/2022]
Abstract
PURPOSE To investigate changes in aqueous humor dynamics during intraocular pressure (IOP) elevation induced by circumlimbal suture in mice. METHODS Ocular hypertension (OHT) was induced by applying a circumlimbal suture behind the limbus in male adult C57BL6/J mice. In the OHT group, the suture was left in place for an average of 8 weeks (n = 10, OHT group). In the sham control group the suture was cut at 2 days (n = 9, sham group) and in the naïve control group (n = 5) no suture was implanted. IOP was measured at baseline across 3 days, 1 h post-suture implantation, and at the chronic endpoint. Anterior segments were assessed using optical coherence tomography (OCT). Episcleral venous pressure (EVP), total outflow facility (C), uveoscleral outflow (Fu) and aqueous humor flow rate (Fin) were determined using a constant-flow infusion model. RESULTS All aqueous dynamic and chronic IOP outcome measures showed no difference between sham and naïve controls (p > 0.05) and thus these groups were combined into a single control group. IOP was elevated in OHT group compared with controls (p < 0.01). Chronic suture implantation did not change pupil size, anterior chamber depth or iridocorneal angles (p > 0.05). EVP was significantly higher in OHT eyes compared to control eyes (p < 0.01). There was no statistical difference in C, Fu and Fin between groups (p > 0.05). A significant linear correlation was found between IOP and EVP (R2 = 0.35, p = 0.001). CONCLUSIONS Circumlimbal suture implantation in mouse eyes results in chronic IOP elevation without angle closure. Chronic IOP elevation is likely to reflect higher EVP.
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Affiliation(s)
- Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Da Zhao
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Cameron J Millar
- North Texas Eye Research Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Christine T O Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia.
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20
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Novikova IN, Manole A, Zherebtsov EA, Stavtsev DD, Vukolova MN, Dunaev AV, Angelova PR, Abramov AY. Adrenaline induces calcium signal in astrocytes and vasoconstriction via activation of monoamine oxidase. Free Radic Biol Med 2020; 159:15-22. [PMID: 32738397 DOI: 10.1016/j.freeradbiomed.2020.07.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 10/23/2022]
Abstract
Adrenaline or epinephrine is a hormone playing an important role in physiology. It is produced de-novo in the brain in very small amounts compared to other catecholamines, including noradrenaline. Although the effects of adrenaline on neurons have been extensively studied, much less is known about the action of this hormone on astrocytes. Here, we studied the effects of adrenaline on astrocytes in primary co-culture of neurons and astrocytes. Application of adrenaline induced calcium signal in both neurons and astrocytes, but only in neurons this effect was dependent on α- and β-receptor antagonists. The effects of adrenaline on astrocytes were less dependent on adrenoreceptors: the antagonist carvedilol had only moderate effect on the calcium signal and the agonist of adrenoreceptors methoxamine induced a signal only in small proportion of the cells. We found that adrenaline in astrocytes activates phospholipase C and subsequent release of calcium from the endoplasmic reticulum. Calcium signal in astrocytes is initiated by the metabolism of adrenaline by the monoamine oxidase (MAO), which activates reactive oxygen species production and induces lipid peroxidation. Inhibitor of MAO selegiline inhibited both adrenaline-induced calcium signal in astrocytes and the vasoconstriction that indicates an important role for monoamine oxidase in adrenaline-induced signalling and function.
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Affiliation(s)
- Irina N Novikova
- Cell Physiology and Pathology Laboratory, Orel State University, Orel, 302026, Russia
| | | | - Evgeny A Zherebtsov
- Cell Physiology and Pathology Laboratory, Orel State University, Orel, 302026, Russia; Optoelectronics and Measurement Techniques Laboratory, University of Oulu, Oulu, 90014, Finland
| | - Dmitry D Stavtsev
- Cell Physiology and Pathology Laboratory, Orel State University, Orel, 302026, Russia
| | - Marina N Vukolova
- Department of Pathophysiology, Sechenov First Moscow State Medical University, Moscow, 119991, Russia
| | - Andrey V Dunaev
- Cell Physiology and Pathology Laboratory, Orel State University, Orel, 302026, Russia
| | - Plamena R Angelova
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queens Square, London, WC1N 3BG, UK
| | - Andrey Y Abramov
- Cell Physiology and Pathology Laboratory, Orel State University, Orel, 302026, Russia; Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queens Square, London, WC1N 3BG, UK.
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21
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Saghiri MA, Suscha A, Wang S, Saghiri AM, Sorenson CM, Sheibani N. Noninvasive temporal detection of early retinal vascular changes during diabetes. Sci Rep 2020; 10:17370. [PMID: 33060607 PMCID: PMC7567079 DOI: 10.1038/s41598-020-73486-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 09/10/2020] [Indexed: 12/15/2022] Open
Abstract
Diabetes associated complications, including diabetic retinopathy and loss of vision, are major health concerns. Detecting early retinal vascular changes during diabetes is not well documented, and only few studies have addressed this domain. The purpose of this study was to noninvasively evaluate temporal changes in retinal vasculature at very early stages of diabetes using fundus images from preclinical models of diabetes. Non-diabetic and Akita/+ male mice with different duration of diabetes were subjected to fundus imaging using a Micron III imaging system. The images were obtained from 4 weeks- (onset of diabetes), 8 weeks-, 16 weeks-, and 24 weeks-old male Akita/+ and non-diabetic mice. In total 104 fundus images were subjected to analysis for various feature extractions. A combination of Canny Edge Detector and Angiogenesis Analyzer plug-ins in ImageJ were utilized to quantify various retinal vascular changes in fundus images. Statistical analyses were conducted to determine significant differences in the various extracted features from fundus images of diabetic and non-diabetic animals. Our novel image analysis method led to extraction of over 20 features. These results indicated that some of these features were significantly changed with a short duration of diabetes, and others remained the same but changed after longer duration of diabetes. These patterns likely distinguish acute (protective) and chronic (damaging) associated changes with diabetes. We show that with a combination of various plugging one can extract over 20 features from retinal vasculature fundus images. These features change during diabetes, thus allowing the quantification of quality of retinal vascular architecture as biomarkers for disease progression. In addition, our method was able to identify unique differences among diabetic mice with different duration of diabetes. The ability to noninvasively detect temporal retinal vascular changes during diabetes could lead to identification of specific markers important in the development and progression of diabetes mediated-microvascular changes, evaluation of therapeutic interventions, and eventual reversal of these changes in order to stop or delay disease progression.
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Affiliation(s)
- Mohammad Ali Saghiri
- Director of Biomaterial and Prosthodontic Laboratory, Department of Restorative Dentistry, Rutgers School of Dental Medicine, Rutgers Biomedical and Health Sciences, MSB C639A, 185 South Orange Avenue, Newark, NJ, 07103, USA.
- Department of Endodontics, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco, CA, USA.
| | - Andrew Suscha
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Shoujian Wang
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | | | - Christine M Sorenson
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Nader Sheibani
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
- Department of Biomedical Engineering, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
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22
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Phan TX, Ton HT, Gulyás H, Pórszász R, Tóth A, Russo R, Kay MW, Sahibzada N, Ahern GP. TRPV1 expressed throughout the arterial circulation regulates vasoconstriction and blood pressure. J Physiol 2020; 598:5639-5659. [PMID: 32944976 DOI: 10.1113/jp279909] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 09/16/2020] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS The functional roles of the capsaicin receptor, TRPV1, outside of sensory nerves are unclear. We mapped TRPV1 in the mouse circulation, revealing extensive expression in the smooth muscle of resistance arterioles supplying skeletal muscle, heart and adipose tissue. Activation of TRPV1 in vascular myocytes constricted arteries, reduced coronary flow in isolated hearts and increased systemic blood pressure. These functional effects were retained after sensory nerve ablation, indicating specific signalling by arterial TRPV1. TRPV1 mediated the vasoconstrictive and blood pressure responses to the endogenous inflammatory lipid lysophosphatidic acid. These results show that TRPV1 in arteriolar myocytes modulates regional blood flow and systemic blood pressure, and suggest that TRPV1 may be a target of vasoactive inflammatory mediators. ABSTRACT The capsaicin receptor, TRPV1, is a key ion channel involved in inflammatory pain signalling. Although mainly studied in sensory nerves, there are reports of TRPV1 expression in isolated segments of the vasculature, but whether the channel localizes to vascular endothelium or smooth muscle is controversial and the distribution and functional roles of TRPV1 in arteries remain unknown. We mapped functional TRPV1 expression throughout the mouse arterial circulation. Analysis of reporter mouse lines TRPV1PLAP-nlacZ and TRPV1-Cre:tdTomato combined with Ca2+ imaging revealed specific localization of TRPV1 to smooth muscle of terminal arterioles in the heart, adipose tissue and skeletal muscle. Capsaicin evoked inward currents (current density ∼10% of sensory neurons) and raised intracellular Ca2+ levels in arterial smooth muscle cells, constricted arterioles ex vivo and in vivo and increased systemic blood pressure in mice and rats. Further, capsaicin markedly and dose-dependently reduced coronary flow. Pharmacological and/or genetic disruption of TRPV1 abolished all these effects of capsaicin as well as vasoconstriction triggered by lysophosphatidic acid, a bioactive lipid generated by platelets and atherogenic plaques. Notably, ablation of sensory nerves did not affect the responses to capsaicin revealing a vascular smooth muscle-restricted signalling mechanism. Moreover, unlike in sensory nerves, TRPV1 function in arteries was resistant to activity-induced desensitization. Thus, TRPV1 activation in vascular myocytes enables a persistent depolarizing current, leading to constriction of coronary, skeletal muscle and adipose arterioles and a sustained increase in systemic blood pressure.
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Affiliation(s)
- Thieu X Phan
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA.,Department of Biology, Vinh University, Vinh, Vietnam
| | - Hoai T Ton
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA.,Department of Biology, Vinh University, Vinh, Vietnam
| | - Hajnalka Gulyás
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Debrecen, Doctoral School of Pharmaceutical Sciences, Debrecen, Hungary
| | - Róbert Pórszász
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Debrecen, Doctoral School of Pharmaceutical Sciences, Debrecen, Hungary
| | - Attila Tóth
- Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Rebekah Russo
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Matthew W Kay
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Niaz Sahibzada
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA
| | - Gerard P Ahern
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA
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23
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Mateus Gonçalves L, Pereira E, Werneck de Castro JP, Bernal-Mizrachi E, Almaça J. Islet pericytes convert into profibrotic myofibroblasts in a mouse model of islet vascular fibrosis. Diabetologia 2020; 63:1564-1575. [PMID: 32424539 PMCID: PMC7354906 DOI: 10.1007/s00125-020-05168-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 04/02/2020] [Indexed: 12/18/2022]
Abstract
AIMS/HYPOTHESIS Islet vascular fibrosis may play an important role in the progression of type 2 diabetes, but there are no mouse models allowing detailed mechanistic studies to understand how a dysfunctional islet microvasculature contributes to diabetes pathogenesis. Here we report that the transgenic AktTg mouse, unlike other mouse strains, shows an increased deposition of extracellular matrix (ECM) proteins in perivascular regions, allowing us to study the cellular mechanisms that lead to islet vascular fibrosis. METHODS Using immunohistochemistry, we labelled the islet microvasculature and ECM in pancreas sections of AktTg mice and human donors and performed lineage tracing to follow the fate of islet pericytes. We compared islet microvascular responses in living pancreas slices from wild-type and AktTg mice. RESULTS We found that vascular pericytes proliferate extensively, convert into profibrotic myofibroblasts and substantially contribute to vascular fibrosis in the AktTg mouse model. The increased deposition of collagen I, fibronectin and periostin within the islet is associated with diminished islet perfusion as well as impaired capillary responses to noradrenaline (norepinephrine) and to high glucose in living pancreas slices. CONCLUSIONS/INTERPRETATION Our study thus illustrates how the AktTg mouse serves to elucidate a cellular mechanism in the development of islet vascular fibrosis, namely a change in pericyte phenotype that leads to vascular dysfunction. Because beta cells in the AktTg mouse are more numerous and larger, and secrete more insulin, in future studies we will test the role beta cell secretory products play in determining the phenotype of pericytes and other cells residing in the islet microenvironment under physiological and pathophysiological conditions. Graphical abstract.
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Affiliation(s)
- Luciana Mateus Gonçalves
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Obesity and Comorbidities Research Center, Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas, SP, Brazil
| | - Elizabeth Pereira
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - João Pedro Werneck de Castro
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Miami VA Health Care System, Miami, FL, 33136, USA
| | - Joana Almaça
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
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24
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Solari E, Marcozzi C, Bistoletti M, Baj A, Giaroni C, Negrini D, Moriondo A. TRPV4 channels' dominant role in the temperature modulation of intrinsic contractility and lymph flow of rat diaphragmatic lymphatics. Am J Physiol Heart Circ Physiol 2020; 319:H507-H518. [PMID: 32706268 DOI: 10.1152/ajpheart.00175.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The lymphatic system drains and propels lymph by extrinsic and intrinsic mechanisms. Intrinsic propulsion depends upon spontaneous rhythmic contractions of lymphatic muscles in the vessel walls and is critically affected by changes in the surrounding tissue like osmolarity and temperature. Lymphatics of the diaphragm display a steep change in contraction frequency in response to changes in temperature, and this, in turn, affects lymph flow. In the present work, we demonstrated in an ex vivo diaphragmatic tissue rat model that diaphragmatic lymphatics express transient receptor potential channels of the vanilloid 4 subfamily (TRPV4) and that their blockade by both the nonselective antagonist Ruthenium Red and the selective antagonist HC-067047 abolished the response of lymphatics to temperature changes. Moreover, the selective activation of TRPV4 channels by means of GSK1016790A mirrored the behavior of vessels exposed to increasing temperatures, pointing out the critical role played by these channels in sensing the temperature of the lymphatic vessels' environment and thus inducing a change in contraction frequency and lymph flow.NEW & NOTEWORTHY The present work addresses the putative receptor system that enables diaphragmatic lymphatics to change intrinsic contraction frequency and thus lymph flow according to the changes in temperature of the surrounding environment, showing that this role can be sustained by TRPV4 channels alone.
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Affiliation(s)
- Eleonora Solari
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Cristiana Marcozzi
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Michela Bistoletti
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Andreina Baj
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Cristina Giaroni
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Daniela Negrini
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Andrea Moriondo
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
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25
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Ma J, Ma Y, Shuaib A, Winship IR. Improved collateral flow and reduced damage after remote ischemic perconditioning during distal middle cerebral artery occlusion in aged rats. Sci Rep 2020; 10:12392. [PMID: 32709950 PMCID: PMC7381676 DOI: 10.1038/s41598-020-69122-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/07/2020] [Indexed: 02/05/2023] Open
Abstract
Circulation through cerebral collaterals can maintain tissue viability until reperfusion is achieved. However, collateral circulation is time limited, and failure of collaterals is accelerated in the aged. Remote ischemic perconditioning (RIPerC), which involves inducing a series of repetitive, transient peripheral cycles of ischemia and reperfusion at a site remote to the brain during cerebral ischemia, may be neuroprotective and can prevent collateral failure in young adult rats. Here, we demonstrate the efficacy of RIPerC to improve blood flow through collaterals in aged (16-18 months of age) Sprague Dawley rats during a distal middle cerebral artery occlusion. Laser speckle contrast imaging and two-photon laser scanning microscopy were used to directly measure flow through collateral connections to ischemic tissue. Consistent with studies in young adult rats, RIPerC enhanced collateral flow by preventing the stroke-induced narrowing of pial arterioles during ischemia. This improved flow was associated with reduced early ischemic damage in RIPerC treated aged rats relative to controls. Thus, RIPerC is an easily administered, non-invasive neuroprotective strategy that can improve penumbral blood flow via collaterals. Enhanced collateral flow supports further investigation as an adjuvant therapy to recanalization therapy and a protective treatment to maintain tissue viability prior to reperfusion.
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Affiliation(s)
- Junqiang Ma
- Neurochemical Research Unit, Department of Psychiatry, 12-127 Clinical Sciences Building, University of Alberta, Edmonton, AB, T6G 2R3, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- First Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong, China
| | - Yonglie Ma
- Neurochemical Research Unit, Department of Psychiatry, 12-127 Clinical Sciences Building, University of Alberta, Edmonton, AB, T6G 2R3, Canada
| | - Ashfaq Shuaib
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Division of Neurology, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Ian R Winship
- Neurochemical Research Unit, Department of Psychiatry, 12-127 Clinical Sciences Building, University of Alberta, Edmonton, AB, T6G 2R3, Canada.
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.
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26
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Shim H, Lee J, Kim S. BOLD fMRI and hemodynamic responses to somatosensory stimulation in anesthetized mice: spontaneous breathing vs. mechanical ventilation. NMR IN BIOMEDICINE 2020; 33:e4311. [PMID: 32297409 PMCID: PMC7317444 DOI: 10.1002/nbm.4311] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/26/2020] [Accepted: 03/25/2020] [Indexed: 06/11/2023]
Abstract
Mouse functional MRI (fMRI) has been of great interest due to the abundance of transgenic models. Due to a mouse's small size, spontaneous breathing has often been used. Because the vascular physiology affecting fMRI might not be controlled normally, its effects on functional responses were investigated with optical intrinsic signal (OIS) imaging and 9.4 T BOLD fMRI. Three conditions were tested in C57BL/6 mice: spontaneous breathing under ketamine and xylazine anesthesia (KX), mechanical ventilation under KX, and mechanical ventilation under isoflurane. Spontaneous breathing under KX induced an average pCO2 of 83 mmHg, whereas a mechanical ventilation condition achieved a pCO2 of 37-41 mmHg within a physiological range. The baseline diameter of arterial and venous vessels was only 7%-9% larger with spontaneous breathing than with mechanical ventilation under KX, but it was much smaller than that in normocapnic isoflurane-anesthetized mice. Three major functional studies were performed. First, CBV-weighted OIS and arterial dilations to 4-second forepaw stimulation were rapid and larger at normocapnia than hypercapnia under KX, but very small under isoflurane. Second, CBV-weighted OIS and arterial dilations by vasodilator acetazolamide were measured for investigating vascular reactivity and were larger in the normocapnic condition than in the hypercapnic condition under KX. Third, evoked OIS and BOLD fMRI responses in the contralateral mouse somatosensory cortex to 20-second forepaw stimulation were faster and larger in the mechanical ventilation than spontaneous breathing. BOLD fMRI peaked at the end of the 20-second stimulation under hypercapnic spontaneous breathing, and at ~9 seconds under mechanical ventilation. The peak amplitude of BOLD fMRI was 2.2% at hypercapnia and ~3.4% at normocapnia. Overall, spontaneous breathing induces sluggish reduced hemodynamic and fMRI responses, but it is still viable for KX anesthesia due to its simplicity, noninvasiveness, and well-localized BOLD activity in the somatosensory cortex.
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Affiliation(s)
- Hyun‐Ji Shim
- Center for Neuroscience Imaging Research (CNIR)Institute for Basic Science (IBS)Suwon16419Republic of Korea
- Department of Health Sciences and Technology, SAIHSTSungkyunkwan UniversitySeoul06355Republic of Korea
| | - Joonyeol Lee
- Center for Neuroscience Imaging Research (CNIR)Institute for Basic Science (IBS)Suwon16419Republic of Korea
- Department of Biomedical EngineeringSungkyunkwan UniversitySuwon16419Republic of Korea
| | - Seong‐Gi Kim
- Center for Neuroscience Imaging Research (CNIR)Institute for Basic Science (IBS)Suwon16419Republic of Korea
- Department of Health Sciences and Technology, SAIHSTSungkyunkwan UniversitySeoul06355Republic of Korea
- Department of Biomedical EngineeringSungkyunkwan UniversitySuwon16419Republic of Korea
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27
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Shan T, Zhao Y, Jiang S, Jiang H. In-vivo hemodynamic imaging of acute prenatal ethanol exposure in fetal brain by photoacoustic tomography. JOURNAL OF BIOPHOTONICS 2020; 13:e201960161. [PMID: 31994834 DOI: 10.1002/jbio.201960161] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 01/18/2020] [Accepted: 01/23/2020] [Indexed: 05/25/2023]
Abstract
Prenatal ethanol exposure (PEE) can lead to structural and functional abnormalities in fetal brain. Although neural developmental deficits due to PEE have been recognized, the immediate effects of PEE on fetal brain vasculature and hemodynamics remain poorly understood. One of the major obstacles that preclude the rapid advancement of studies on fetal vascular dynamics is the limitation of the imaging techniques. Thus, a technique for noninvasive in-vivo imaging of fetal vasculature and hemodynamics is desirable. In this study, we explored the dynamic changes of the vessel dimeter, density and oxygen saturation in fetal brain after acute maternal ethanol exposure in the second-trimester equivalent murine model using a real-time photoacoustic tomography system we developed for imaging embryo of small animals. The results indicate a significant decrease in fetal brain vessel diameter, perfusion and oxygen saturation. This work demonstrated that PAT can provide high-resolution noninvasive imaging ability to monitor fetal vascular dynamics.
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Affiliation(s)
- Tianqi Shan
- Department of Biomedical Engineering, University of Florida, Gainesville, Florida
| | - Yuan Zhao
- School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, China
| | - Shixie Jiang
- Department of Psychiatry and Behavioral Neurosciences, University of South Florida, Tampa, Florida
| | - Huabei Jiang
- Department of Medical Engineering, University of South Florida, Tampa, Florida
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28
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Ma J, Ma Y, Shuaib A, Winship IR. Impaired Collateral Flow in Pial Arterioles of Aged Rats During Ischemic Stroke. Transl Stroke Res 2020; 11:243-253. [PMID: 31203565 PMCID: PMC7067739 DOI: 10.1007/s12975-019-00710-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/02/2019] [Accepted: 06/05/2019] [Indexed: 02/05/2023]
Abstract
Cerebral collateral circulation and age are critical factors in determining outcome from acute ischemic stroke. Aging may lead to rarefaction of cerebral collaterals, and thereby accelerate ischemic injury by reducing penumbral blood flow. Dynamic changes in pial collaterals after onset of cerebral ischemia may vary with age but have not been extensively studied. Here, laser speckle contrast imaging (LSCI) and two-photon laser scanning microscopy (TPLSM) were combined to monitor cerebral pial collaterals between the anterior cerebral artery (ACA) and the middle cerebral artery (MCA) in young adult and aged male Sprague Dawley rats during distal middle cerebral artery occlusion (dMCAo). Histological analysis showed that aged rats had significantly greater volumes of ischemic damage than young rats. LSCI showed that cerebral collateral perfusion declined over time after stroke in aged and young rats, and that this decline was significantly greater in aged rats. TPLSM demonstrated that pial arterioles narrowed faster after dMCAo in aged rats compared to young adult rats. Notably, while arteriole vessel narrowing was comparable 4.5 h after ischemic onset in aged and young adult rats, red blood cell velocity was stable in young adults but declined over time in aged rats. Overall, red blood cell flux through pial arterioles was significantly reduced at all time-points after 90 min post-dMCAo in aged rats relative to young adult rats. Thus, collateral failure is more severe in aged rats with significantly impaired pial collateral dynamics (reduced diameter, red blood cell velocity, and red blood cell flux) relative to young adult rats.
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Affiliation(s)
- Junqiang Ma
- Neurochemical Research Unit, Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, 12-127 Clinical Sciences Building, Edmonton, AB, T6G 2R3, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- First Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong, China
| | - Yonglie Ma
- Neurochemical Research Unit, Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, 12-127 Clinical Sciences Building, Edmonton, AB, T6G 2R3, Canada
| | - Ashfaq Shuaib
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Division of Neurology, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Ian R Winship
- Neurochemical Research Unit, Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, 12-127 Clinical Sciences Building, Edmonton, AB, T6G 2R3, Canada.
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.
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29
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Shariflou S, Agar A, Rose K, Bowd C, Golzan SM. Objective Quantification of Spontaneous Retinal Venous Pulsations Using a Novel Tablet-Based Ophthalmoscope. Transl Vis Sci Technol 2020; 9:19. [PMID: 32818106 PMCID: PMC7396170 DOI: 10.1167/tvst.9.4.19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 12/24/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose Dynamic assessment of retinal vascular characteristics can aid in identifying glaucoma-specific biomarkers. More specifically, a loss of spontaneous retinal venous pulsations (SVPs) has been reported in glaucoma, but a lack of readily available tools has limited the ability to explore the full potential of SVP analysis in glaucoma assessment. Advancements in smart technology have paved the way for the development of portable, noninvasive, and inexpensive imaging modalities. By combining off-the-shelf optical elements and smart devices, the current study aims to determine whether SVPs can be detected and quantified using a novel tablet-based ophthalmoscope in glaucoma and glaucoma suspects. Methods Thirty patients, including 21 with confirmed glaucoma (9 men; average age 75 ± 8 years) and 9 glaucoma suspects (5 men; average age 64 ± 9 years), were studied. All patients had intraocular pressure measurements, Humphrey visual field assessment, optical coherence tomography, and a 10-second videoscopy of the retinal circulation. The retinal vasculature recordings (46° field of view at 30 frames per second) were analyzed to extract SVP amplitudes. Results SVPs were detected and quantified in 100% of patients with glaucoma and those with suspected glaucoma using the novel device. The average SVP amplitudes in glaucoma and glaucoma suspects were 42.6% ± 10.7% and 34% ± 6.7%, respectively. Conclusions Our results suggest that a novel tablet-based ophthalmoscope can aid in documenting and objectively quantifying SVPs in all patients. Translational Relevance Outcomes of this study provide an innovative, portable, noninvasive, and inexpensive solution for objective assessment of SVPs, which may have clinical relevance in glaucoma screening.
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Affiliation(s)
- Sahar Shariflou
- Vision Science Group, Discipline of Orthoptics, Graduate School of Health, University of Technology Sydney, NSW, Australia
| | - Ashish Agar
- Vision Science Group, Discipline of Orthoptics, Graduate School of Health, University of Technology Sydney, NSW, Australia
- Ophthalmology Department, Prince of Wales Hospital, Sydney, NSW, Australia
- Department of Ophthalmology, University of New South Wales, Sydney, NSW, Australia
- Marsden Eye Specialists, Sydney, NSW, Australia
| | - Kathryn Rose
- Vision Science Group, Discipline of Orthoptics, Graduate School of Health, University of Technology Sydney, NSW, Australia
| | - Christopher Bowd
- Hamilton Glaucoma Centre, Shiley Eye Institute, University of California, San Diego, San Diego, CA, USA
| | - S. Mojtaba Golzan
- Vision Science Group, Discipline of Orthoptics, Graduate School of Health, University of Technology Sydney, NSW, Australia
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30
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Solari E, Marcozzi C, Bartolini B, Viola M, Negrini D, Moriondo A. Acute Exposure of Collecting Lymphatic Vessels to Low-Density Lipoproteins Increases Both Contraction Frequency and Lymph Flow: An In Vivo Mechanical Insight. Lymphat Res Biol 2019; 18:146-155. [PMID: 31526222 DOI: 10.1089/lrb.2019.0040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Background: Lymphatic vessels drain fluids and solutes from interstitial spaces and serosal cavities. Among the solutes, low-density lipoproteins (LDL) are drained and can be detected in peripheral lymph, where they have been reported to exert a modulatory action on lymphatic vessels intrinsic contraction rate. In the present work, we investigated lymphatic vessel mechanical properties (contraction frequency and amplitude) that may be modulated by LDL application and the consequence on lymph flow. Methods and Results: Human-derived LDL were resuspended in phosphate-buffered saline (PBS) and microinjected in the interstitial space surrounding spontaneously contracting lymphatic vessels of the rat diaphragm, in vivo. Vessels' contraction rate and diameter were measured in control conditions (PBS) and after LDL injection. Lymph flow (Jlymph) was computed from contraction rate and diameter change. In some animals, after the recording procedure, diaphragmatic tissue samples were excised and immunostained with antilymphatic muscle (LM) actin to investigate the correlation between LM signal level and contraction amplitude. Data indicate a positive, saturating correlation between the abundance of LM actin and contraction amplitude, and LDL microinjection caused an acute increase in contraction frequency (+126%), a reduction of contraction amplitude to 75% of that obtained after PBS injection, and a +63% increase in Jlymph. Conclusions: From our in vivo analysis of the mechanical parameters affected by LDL, Jlymph was increased by a predominant effect on the contraction rate rather than amplitude, suggesting that the still elusive messaging system might be linked to the pacemaker sites.
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Affiliation(s)
- Eleonora Solari
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Cristiana Marcozzi
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Barbara Bartolini
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Manuela Viola
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Daniela Negrini
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Andrea Moriondo
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
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31
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Diéguez-Hurtado R, Kato K, Giaimo BD, Nieminen-Kelhä M, Arf H, Ferrante F, Bartkuhn M, Zimmermann T, Bixel MG, Eilken HM, Adams S, Borggrefe T, Vajkoczy P, Adams RH. Loss of the transcription factor RBPJ induces disease-promoting properties in brain pericytes. Nat Commun 2019; 10:2817. [PMID: 31249304 PMCID: PMC6597568 DOI: 10.1038/s41467-019-10643-w] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 05/15/2019] [Indexed: 02/06/2023] Open
Abstract
Sufficient vascular supply is indispensable for brain development and function, whereas dysfunctional blood vessels are associated with human diseases such as vascular malformations, stroke or neurodegeneration. Pericytes are capillary-associated mesenchymal cells that limit vascular permeability and protect the brain by preserving blood-brain barrier integrity. Loss of pericytes has been linked to neurodegenerative changes in genetically modified mice. Here, we report that postnatal inactivation of the Rbpj gene, encoding the transcription factor RBPJ, leads to alteration of cell identity markers in brain pericytes, increases local TGFβ signalling, and triggers profound changes in endothelial behaviour. These changes, which are not mimicked by pericyte ablation, imperil vascular stability and induce the acquisition of pathological landmarks associated with cerebral cavernous malformations. In adult mice, loss of Rbpj results in bigger stroke lesions upon ischemic insult. We propose that brain pericytes can acquire deleterious properties that actively enhance vascular lesion formation and promote pathogenic processes. Pericytes are perivascular cells essential for blood-brain barrier maintenance. Here Diéguez-Hurtado et al. show that depletion of the transcription factor RBPJ in pericytes affects their molecular identity and disturbs endothelial cell behaviour, inducing the formation of vascular lesions in the brain.
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Affiliation(s)
- Rodrigo Diéguez-Hurtado
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, 48149, Münster, Germany.,Faculty of Medicine, University of Münster, 48149, Münster, Germany
| | - Katsuhiro Kato
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, 48149, Münster, Germany
| | | | - Melina Nieminen-Kelhä
- Department of Neurosurgery, Charité-Universitätsmedizin, Charitéplatz 1, Berlin, 10117, Germany.,Berlin Institute of Health, Charitéplatz 1, 10117, Berlin, Germany
| | - Hendrik Arf
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, 48149, Münster, Germany
| | - Francesca Ferrante
- Institute of Biochemistry, University of Giessen, Friedrichstrasse 24, 35392, Giessen, Germany
| | - Marek Bartkuhn
- Institute for Genetics, University of Giessen, Heinrich-Buff-Ring 58-62, 35392, Giessen, Germany
| | - Tobias Zimmermann
- Bioinformatics and Systems Biology, University of Giessen, Heinrich-Buff-Ring 58-62, 35392, Giessen, Germany
| | - M Gabriele Bixel
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, 48149, Münster, Germany
| | - Hanna M Eilken
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, 48149, Münster, Germany.,Bayer AG, Aprather Weg 18a, 42113, Wuppertal, Germany
| | - Susanne Adams
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, 48149, Münster, Germany
| | - Tilman Borggrefe
- Institute of Biochemistry, University of Giessen, Friedrichstrasse 24, 35392, Giessen, Germany
| | - Peter Vajkoczy
- Department of Neurosurgery, Charité-Universitätsmedizin, Charitéplatz 1, Berlin, 10117, Germany. .,Berlin Institute of Health, Charitéplatz 1, 10117, Berlin, Germany.
| | - Ralf H Adams
- Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, 48149, Münster, Germany. .,Faculty of Medicine, University of Münster, 48149, Münster, Germany.
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Lawton PF, Lee MD, Saunter CD, Girkin JM, McCarron JG, Wilson C. VasoTracker, a Low-Cost and Open Source Pressure Myograph System for Vascular Physiology. Front Physiol 2019; 10:99. [PMID: 30846942 PMCID: PMC6393368 DOI: 10.3389/fphys.2019.00099] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/28/2019] [Indexed: 01/12/2023] Open
Abstract
Pressure myography, one of the most commonly used techniques in vascular research, measures the diameter of isolated, pressurized arteries to assess the functional activity of smooth muscle and endothelial cells. Despite the widespread adoption of this technique for assessing vascular function, there are only a small number of commercial systems and these are expensive. Here, we introduce a complete, open source pressure myograph system and analysis software, VasoTracker, that can be set-up for approximately 10% of the cost of commercial alternatives. We report on the development of VasoTracker and demonstrate its ability to assess various components of vascular reactivity. A unique feature of the VasoTracker platform is the publicly accessible website (http://www.vasotracker.com/) that documents how to assemble and use this affordable, adaptable, and expandable pressure myograph.
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Affiliation(s)
- Penelope F. Lawton
- Centre for Advanced Instrumentation, Biophysical Sciences Institute, Department of Physics, Durham University, Durham, United Kingdom
| | - Matthew D. Lee
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Christopher D. Saunter
- Centre for Advanced Instrumentation, Biophysical Sciences Institute, Department of Physics, Durham University, Durham, United Kingdom
| | - John M. Girkin
- Centre for Advanced Instrumentation, Biophysical Sciences Institute, Department of Physics, Durham University, Durham, United Kingdom
| | - John G. McCarron
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Calum Wilson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
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Park H, You N, Lee J, Suh M. Longitudinal study of hemodynamics and dendritic membrane potential changes in the mouse cortex following a soft cranial window installation. NEUROPHOTONICS 2019; 6:015006. [PMID: 30820438 PMCID: PMC6387987 DOI: 10.1117/1.nph.6.1.015006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 01/25/2019] [Indexed: 05/21/2023]
Abstract
The soft cranial window using polydimethylsiloxane allows direct multiple access to neural tissue during long-term monitoring. However, the chronic effects of soft window installation on the brain have not been fully studied. Here, we investigate the long-term effects of soft window installation on sensory-evoked cerebral hemodynamics and neuronal activity. We monitored the brain tissue immunocytohistology for 6 weeks postinstallation. Heightened reactive astrocytic and microglia levels were found at 2 weeks postinstallation. By 6 weeks postinstallation, mice had expression levels similar to those of normal animals. We recorded sensory-evoked hemodynamics of the barrel cortex and LFP during whisker stimulation at these time points. Animals at 6 weeks postinstallation showed stronger hemodynamic responses and focalized barrel mapping than 2-week postoperative mice. LFP recordings of 6-week postoperative mice also showed higher neural activity at the barrel column corresponding to the stimulated whisker. Furthermore, the expression level of interleukin- 1 β was highly upregulated at 2 weeks postinstallation. When we treated animals postoperatively with minocycline plus N-acetylcystein, a drug-suppressing inflammatory cytokine, these animals did not show declined hemodynamic responses and neuronal activities. This result suggests that neuroinflammation following soft window installation may alter hemodynamic and neuronal responses upon sensory stimulation.
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Affiliation(s)
- Hyejin Park
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
- Sungkyunkwan University, Department of Biological Sciences, Suwon, Republic of Korea
- Sungkyunkwan University, Biomedical Institute for Convergence, Suwon, Republic of Korea
| | - Nayeon You
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
- Sungkyunkwan University, Department of Biomedical Engineering, Suwon, Republic of Korea
| | - Juheon Lee
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
- Sungkyunkwan University, Department of Biomedical Engineering, Suwon, Republic of Korea
| | - Minah Suh
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
- Sungkyunkwan University, Biomedical Institute for Convergence, Suwon, Republic of Korea
- Sungkyunkwan University, Department of Biomedical Engineering, Suwon, Republic of Korea
- Sungkyunkwan University, SAHIST, Suwon, Republic of Korea
- Address all correspondence to Minah Suh, E-mail:
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Solari E, Marcozzi C, Negrini D, Moriondo A. Fluid Osmolarity Acutely and Differentially Modulates Lymphatic Vessels Intrinsic Contractions and Lymph Flow. Front Physiol 2018; 9:871. [PMID: 30026707 PMCID: PMC6041695 DOI: 10.3389/fphys.2018.00871] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 06/18/2018] [Indexed: 12/19/2022] Open
Abstract
Lymph formation and propulsion rely on an extrinsic mechanism based on the forces that surrounding tissues exert upon the vessel wall and lumen and an intrinsic mechanism based on spontaneous, rhythmic contractions of the lymphatic muscle layer of collecting vessels. The two spontaneous pacemakers described in literature involve chloride-dependent depolarizations (STDs) and If-like currents, both giving rise to a variable contraction frequency (fc) of lymphatic vessels functional units (lymphangions). Several stimuli have been shown to modulate fc, such as temperature, shear stress, and several tissue chemical modulators (prostaglandins, norepinephrine, acetylcholine, substance P, and others). However, no detailed description is present in literature on the acute modulation of fc by means of osmolarity change of the surrounding interstitial space. Using a well-developed ex-vivo rat diaphragmatic preparation, in which osmolarity was changed by varying the concentration of D-mannitol in the perfusing solution and in later experiments the concentration of NaCl and then of Na+ and Cl− ions separately by ionic substitution, we provide detailed experimental evidences that a stepwise increase in osmolarity from control value (308 mOsm) up to 324 mOsm caused a reduction of fc down to ~-70% within the first 14 min, and that a stepwise decrease in osmolarity up to 290 mOsm induced an early fc increase to ~+34% of control, followed by a decline to an fc of ~-18% of control value. These variations were more dramatic when the same osmolarity changes were obtained by varying NaCl and/or Na+ or Cl− ions concentration, which caused an almost complete arrest of spontaneous contractility within 14 min from the application. Diastolic and systolic diameters and stroke volume were not affected by osmolarity changes, so that modulation of lymph flow closely followed that of fc. Modulation of lymph flow secondary to osmolarity changes is relevant if one considers that interstitial fluid balance is also dependent upon lymph drainage, and thus it is possible that, at least in the acute phase following variations of interstitial fluid osmolarity, its volume control might eventually be impaired due to the reduced or in the worst scenario null lymph drainage.
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Affiliation(s)
- Eleonora Solari
- Department of Medicine and Surgery, Università degli Studi dell'Insubria, Varese, Italy
| | - Cristiana Marcozzi
- Department of Medicine and Surgery, Università degli Studi dell'Insubria, Varese, Italy
| | - Daniela Negrini
- Department of Medicine and Surgery, Università degli Studi dell'Insubria, Varese, Italy
| | - Andrea Moriondo
- Department of Medicine and Surgery, Università degli Studi dell'Insubria, Varese, Italy
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Almaça J, Weitz J, Rodriguez-Diaz R, Pereira E, Caicedo A. The Pericyte of the Pancreatic Islet Regulates Capillary Diameter and Local Blood Flow. Cell Metab 2018; 27:630-644.e4. [PMID: 29514070 PMCID: PMC5876933 DOI: 10.1016/j.cmet.2018.02.016] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 12/15/2017] [Accepted: 02/15/2018] [Indexed: 12/20/2022]
Abstract
Efficient insulin secretion requires a well-functioning pancreatic islet microvasculature. The dense network of islet capillaries includes the islet pericyte, a cell that has barely been studied. Here we show that islet pericytes help control local blood flow by adjusting islet capillary diameter. Islet pericytes cover 40% of the microvasculature, are contractile, and are innervated by sympathetic axons. Sympathetic adrenergic input increases pericyte activity and reduces capillary diameter and local blood flow. By contrast, activating beta cells by increasing glucose concentration inhibits pericytes, dilates islet capillaries, and increases local blood flow. These effects on pericytes are mediated by endogenous adenosine, which is likely derived from ATP co-released with insulin. Pericyte coverage of islet capillaries drops drastically in type 2 diabetes, suggesting that, under diabetic conditions, islets lose this mechanism to control their own blood supply. This may lead to inadequate insulin release into the circulation, further deteriorating glycemic control.
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Affiliation(s)
- Joana Almaça
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
| | - Jonathan Weitz
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Molecular Cell and Developmental Biology Program, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Rayner Rodriguez-Diaz
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Elizabeth Pereira
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Alejandro Caicedo
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; Program in Neuroscience, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
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36
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Hui F, Nguyen CTO, He Z, Vingrys AJ, Gurrell R, Fish RL, Bui BV. Retinal and Cortical Blood Flow Dynamics Following Systemic Blood-Neural Barrier Disruption. Front Neurosci 2017; 11:568. [PMID: 29075176 PMCID: PMC5643486 DOI: 10.3389/fnins.2017.00568] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 09/28/2017] [Indexed: 12/11/2022] Open
Abstract
To consider whether imaging retinal vasculature may be used as a marker for cortical vessels, we compared fluorescein angiography flow dynamics before and after pharmacological disruption of blood-neural barriers. Sodium fluorescein (1%, 200 μl/kg) was intravenously delivered in anesthetized adult Long Evans rats (n = 44, brain = 18, retina = 26). In the brain cohort, a cranial window was created to allow direct visualization of surface cortical vessels. Video fluorescein angiography was captured using a rodent retinal camera at 30 frames/second and fluorescence intensity profiles were evaluated for the time to reach 50% brightness (half-rise), 50% decay (half-fall), and the plateau level of remnant fluorescence (offset, %). Cortical vessels fluoresced earlier (artery half-rise: 5.6 ± 0.2 s) and decayed faster (half-fall: 10.3 ± 0.2 s) compared to retinal vasculature. Cortical vessels also had a considerably higher offset, particularly in the capillaries/extravascular space (41.4 ± 2.7%) whereas pigment in the retina reduces such residual fluorescence. In a sub-cohort of animals, sodium deoxycholate (DOC, 0.06 M dissolved in sterile saline, 1 mL) was delivered intravenously to cause simultaneous disruption of the blood-brain and blood-retinal barriers. A separate group received saline as vehicle control. Fluorescein angiography was re-measured at 6 and 24 h after drug infusion and evaluated by comparing flow dynamics to the upper quartile (75%) of the control group. Retinal vasculature was more sensitive to DOC-induced disruption with a higher fluorescence offset at 6 h (47.3 ± 10.6%). A delayed effect was seen in cortical vessels with a higher offset evident only at 24 h (65.6 ± 10.1%). Here we have developed a method to quantitatively compare fluorescein angiography dynamics in the retina and superficial cortical vessels. Our results show that systemic disruption of blood-neural barriers causes vascular leakage in both tissues but earlier in the retina suggesting that pharmacological blood-neural barrier disruption may be detected earlier in the eye than in cortical vasculature.
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Affiliation(s)
- Flora Hui
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Christine T. O. Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Zheng He
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Algis J. Vingrys
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Rachel Gurrell
- Neuroscience and Pain Research Unit, Pfizer, Cambridge, United Kingdom
| | - Rebecca L. Fish
- Neuroscience and Pain Research Unit, Pfizer, Cambridge, United Kingdom
| | - Bang V. Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
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Solari E, Marcozzi C, Negrini D, Moriondo A. Temperature-dependent modulation of regional lymphatic contraction frequency and flow. Am J Physiol Heart Circ Physiol 2017; 313:H879-H889. [PMID: 28778912 DOI: 10.1152/ajpheart.00267.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/21/2017] [Accepted: 08/02/2017] [Indexed: 11/22/2022]
Abstract
Lymph drainage and propulsion are sustained by an extrinsic mechanism, based on mechanical forces acting from the surrounding tissues against the wall of lymphatic vessels, and by an intrinsic mechanism attributable to active spontaneous contractions of the lymphatic vessel muscle. Despite being heterogeneous, the mechanisms underlying the generation of spontaneous contractions share a common biochemical nature and are thus modulated by temperature. In this study, we challenged excised tissues from rat diaphragm and hindpaw, endowed with spontaneously contracting lymphatic vessels, to temperatures from 24°C (hindpaw) or 33°C (diaphragmatic vessels) to 40°C while measuring lymphatic contraction frequency (fc) and amplitude. Both vessel populations displayed a sigmoidal relationship between fc and temperature, each centered around the average temperature of surrounding tissue (36.7 diaphragmatic and 32.1 hindpaw lymphatics). Although the slope factor of the sigmoidal fit to the fc change of hindpaw vessels was 2.3°C·cycles-1·min-1, a value within the normal range displayed by simple biochemical reactions, the slope factor of the diaphragmatic lymphatics was 0.62°C·cycles-1·min-1, suggesting the added involvement of temperature-sensing mechanisms. Lymph flow calculated as a function of temperature confirmed the relationship observed on fc data alone and showed that none of the two lymphatic vessel populations would be able to adapt to the optimal working temperature of the other tissue district. This poses a novel question whether lymphatic vessels might not adapt their function to accommodate the change if exposed to a surrounding temperature, which is different from their normal condition.NEW & NOTEWORTHY This study demonstrates to what extent lymphatic vessel intrinsic contractility and lymph flow are modulated by temperature and that this modulation is dependent on the body district that the vessels belong to, suggesting a possible functional misbehavior should lymphatic vessels be exposed to a chronically different temperature.
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Affiliation(s)
- Eleonora Solari
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Cristiana Marcozzi
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Daniela Negrini
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Andrea Moriondo
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
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Ma J, Ma Y, Dong B, Bandet MV, Shuaib A, Winship IR. Prevention of the collapse of pial collaterals by remote ischemic perconditioning during acute ischemic stroke. J Cereb Blood Flow Metab 2017; 37:3001-3014. [PMID: 27909265 PMCID: PMC5536804 DOI: 10.1177/0271678x16680636] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 09/23/2016] [Accepted: 10/30/2016] [Indexed: 02/05/2023]
Abstract
Collateral circulation is a key variable determining prognosis and response to recanalization therapy during acute ischemic stroke. Remote ischemic perconditioning (RIPerC) involves inducing peripheral ischemia (typically in the limbs) during stroke and may reduce perfusion deficits and brain damage due to cerebral ischemia. In this study, we directly investigated pial collateral flow augmentation due to RIPerC during distal middle cerebral artery occlusion (MCAo) in rats. Blood flow through pial collaterals between the anterior cerebral artery (ACA) and the MCA was assessed in male Sprague Dawley rats using in vivo laser speckle contrast imaging (LSCI) and two photon laser scanning microscopy (TPLSM) during distal MCAo. LSCI and TPLSM revealed that RIPerC augmented collateral flow into distal MCA segments. Notably, while control rats exhibited an initial dilation followed by a progressive narrowing of pial arterioles 60 to 150-min post-MCAo (constricting to 80-90% of post-MCAo peak diameter), this constriction was prevented or reversed by RIPerC (such that vessel diameters increased to 105-110% of post-MCAo, pre-RIPerC diameter). RIPerC significantly reduced early ischemic damage measured 6 h after stroke onset. Thus, prevention of collateral collapse via RIPerC is neuroprotective and may facilitate other protective or recanalization therapies by improving blood flow in penumbral tissue.
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Affiliation(s)
- Junqiang Ma
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- The First Affiliated Hospital, Shantou University Medical College, Shantou, China
| | - Yonglie Ma
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Bin Dong
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Mischa V Bandet
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Ashfaq Shuaib
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Medicine, Division of Neurology, University of Alberta, Edmonton, AB, Canada
| | - Ian R Winship
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- Ian R Winship, 12-127 Clinical Sciences Building, Edmonton, AB T6G 2R3, Canada.
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Li H, Bui BV, Cull G, Wang F, Wang L. Glial Cell Contribution to Basal Vessel Diameter and Pressure-Initiated Vascular Responses in Rat Retina. Invest Ophthalmol Vis Sci 2017; 58:1-8. [PMID: 28055098 PMCID: PMC5225997 DOI: 10.1167/iovs.16-20804] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to test the hypothesis that retinal glial cells modify basal vessel diameter and pressure-initiated vascular regulation in rat retina. Methods In rats, L-2-aminoadipic acid (LAA, 10 nM) was intravitreally injected to inhibit glial cell activity. Twenty-four hours following injection, retinal glial intracellular calcium (Ca2+) was labeled with the fluorescent calcium indicator Fluo-4/AM (F4, 1 mM). At 110 minutes after injection, intraocular pressure (IOP) was elevated from 20 to 50 mm Hg. Prior to and during IOP elevation, Ca2+ and retinal vessel diameter were assessed using a spectral-domain optical coherence tomography/confocal scanning laser ophthalmoscope. Dynamic changes in Ca2+ and diameter from IOP elevation were quantified. The response in LAA-treated eyes was compared with vehicle treated control eyes. Results L-2-Aminoadipic acid treatment significantly reduced F4-positive cells in the retina (LAA, 16 ± 20 vs. control, 55 ± 37 cells/mm2; P = 0.02). Twenty-four hours following LAA treatment, basal venous diameter was increased from 38.9 ± 3.9 to 51.8 ± 6.4 μm (P < 0.0001, n = 20), whereas arterial diameter was unchanged (from 30.3 ± 3.5 to 30.7 ± 2.8 μm; P = 0.64). In response to IOP elevation, LAA-treated eyes showed a smaller increase in glial cell Ca2+ around both arteries and veins in comparison with control (P < 0.001 for both). There was also significantly greater IOP-induced vasoconstriction in both vessel types (P = 0.05 and P = 0.02, respectively; n = 6 each). Conclusions The results suggest that glial cells can modulate basal retinal venous diameter and contribute to pressure-initiated vascular responses.
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Affiliation(s)
- Hui Li
- Department of Ophthalmology, The Tenth People's Hospital, Shanghai, Tongji University School of Medicine, Shanghai, China 2Devers Eye Institute, Legacy Research Institute, Portland, Oregon, USA
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Grant Cull
- Devers Eye Institute, Legacy Research Institute, Portland, Oregon, USA
| | - Fang Wang
- Department of Ophthalmology, The Tenth People's Hospital, Shanghai, Tongji University School of Medicine, Shanghai, China
| | - Lin Wang
- Department of Ophthalmology, The Tenth People's Hospital, Shanghai, Tongji University School of Medicine, Shanghai, China 2Devers Eye Institute, Legacy Research Institute, Portland, Oregon, USA
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van der Putten MA, Brewer JM, Harvey AR. Multispectral oximetry of murine tendon microvasculature with inflammation. BIOMEDICAL OPTICS EXPRESS 2017; 8:2896-2905. [PMID: 28663914 PMCID: PMC5480437 DOI: 10.1364/boe.8.002896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/13/2017] [Accepted: 04/24/2017] [Indexed: 06/07/2023]
Abstract
We report a novel multispectral imaging technique for localised measurement of vascular oxygen saturation (SO2) in vivo. Annular back-illumination is generated using a Schwarzchild-design reflective objective. Analysis of multispectral data is performed using a calibration-free oximetry algorithm. This technique is applied to oximetry in mice to measure SO2 in microvasculature supplying inflamed tendon tissue in the hind leg. Average SO2 for controls was 94.8 ± 7.0 % (N = 6), and 84.0 ± 13.5 % for mice with inflamed tendon tissue (N = 6). We believe this to be the first localised measurement of hypoxia in tendon microvasculature due to inflammation. Quantification of localised SO2 is important for the study of inflammatory diseases such as rheumatoid arthritis, where hypoxia is thought to play a role in pathogenesis.
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Affiliation(s)
| | - James M. Brewer
- Institute for Infection, Immunity & Inflammation, University of Glasgow, G12 8QQ,
UK
| | - Andrew R. Harvey
- School of Physics & Astronomy, University of Glasgow, G12 8QQ,
UK
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41
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Reactivity in the human retinal microvasculature measured during acute gas breathing provocations. Sci Rep 2017; 7:2113. [PMID: 28522835 PMCID: PMC5437020 DOI: 10.1038/s41598-017-02344-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 04/10/2017] [Indexed: 11/11/2022] Open
Abstract
Although changes in vessel diameter following gas perturbation have been documented in retinal arterioles and venules, these responses have yet to be quantified in the smallest vessels of the human retina. Here, using in vivo adaptive optics, we imaged 3–25 µm diameter vessels of the human inner retinal circulation and monitored the effects of altered gas-breathing conditions. During isocapnic hyperoxia, definite constrictions were seen in 51% of vessel segments (mean ± SD for pre-capillary arterioles −9.5 ± 3.0%; capillaries −11.8 ± 3.3%; post-capillary venules −6.3 ± 2.8%); these are comparable with responses previously reported in larger vessels. During isoxic hypercapnia, definite dilations were seen in 47% of vessel segments (mean ± SD for pre-capillary arterioles +9.8 ± 1.5%; capillaries +13.7 ± 3.8%; post-capillary venules +7.5 ± 4.2%); these are proportionally greater than responses previously reported in larger vessels. The magnitude of these proportional changes implies that the capillary beds themselves play an important role in the retinal response to changes in carbon dioxide levels. Interestingly, the distribution of microvascular responses shown here differs from our previously reported responses to flicker stimulation, suggesting differences in the way blood supply is coordinated following gas perturbation and altered neural activity.
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Hawkins VE, Takakura AC, Trinh A, Malheiros-Lima MR, Cleary CM, Wenker IC, Dubreuil T, Rodriguez EM, Nelson MT, Moreira TS, Mulkey DK. Purinergic regulation of vascular tone in the retrotrapezoid nucleus is specialized to support the drive to breathe. eLife 2017; 6. [PMID: 28387198 PMCID: PMC5422071 DOI: 10.7554/elife.25232] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 04/06/2017] [Indexed: 11/24/2022] Open
Abstract
Cerebral blood flow is highly sensitive to changes in CO2/H+ where an increase in CO2/H+ causes vasodilation and increased blood flow. Tissue CO2/H+ also functions as the main stimulus for breathing by activating chemosensitive neurons that control respiratory output. Considering that CO2/H+-induced vasodilation would accelerate removal of CO2/H+ and potentially counteract the drive to breathe, we hypothesize that chemosensitive brain regions have adapted a means of preventing vascular CO2/H+-reactivity. Here, we show in rat that purinergic signaling, possibly through P2Y2/4 receptors, in the retrotrapezoid nucleus (RTN) maintains arteriole tone during high CO2/H+ and disruption of this mechanism decreases the CO2ventilatory response. Our discovery that CO2/H+-dependent regulation of vascular tone in the RTN is the opposite to the rest of the cerebral vascular tree is novel and fundamentally important for understanding how regulation of vascular tone is tailored to support neural function and behavior, in this case the drive to breathe. DOI:http://dx.doi.org/10.7554/eLife.25232.001 We breathe to help us take oxygen into the body and remove carbon dioxide. Our cells use the oxygen to break down food to release energy, and as they do so they produce carbon dioxide as a waste product. Cells release this carbon dioxide back into the bloodstream so that it can be transported to the lungs to be breathed out. Carbon dioxide also makes the blood more acidic; if the blood becomes too acidic, tissues and organs may not work properly. The brain uses roughly 25% of the oxygen consumed by the body and is particularly sensitive to the levels of gases and acidity in the blood. It has been known for more than a century that increased carbon dioxide causes blood vessels in the brain to widen, allowing the excess carbon dioxide to be carried away quickly. More recent work has shown that increased carbon dioxide also activates neurons called respiratory chemoreceptors. These in turn activate the brain centers that drive breathing, causing us to breathe more rapidly to help us remove surplus carbon dioxide. But this scenario contains a paradox. If high levels of carbon dioxide cause widening of the blood vessels in the brain regions that contain respiratory chemoreceptors, this should, in theory, wash out that important stimulus, reducing the drive to breathe. So how does the brain prevent this unhelpful response? By studying the brains of adult rats, Hawkins et al. show that different rules apply to the brain centers that control breathing compared to other areas of the brain. In one such region, if the blood becomes too acidic, support cells called astrocytes release chemical signals called purines. This counteracts the tendency of high carbon dioxide levels to widen blood vessels in this region, and instead causes these vessels to become narrower. This mechanism ensures that local levels of carbon dioxide in respiratory brain centers remain in tune with the demands of local networks, thereby maintaining the drive to breathe. The next challenges are to identify the molecular mechanisms that control the diameter of blood vessels in brain regions containing respiratory chemoreceptors, and to find out whether drugs that modulate these mechanisms have the potential to treat some respiratory conditions. DOI:http://dx.doi.org/10.7554/eLife.25232.002
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Affiliation(s)
- Virginia E Hawkins
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, United States
| | - Ana C Takakura
- Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Ashley Trinh
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, United States
| | - Milene R Malheiros-Lima
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Colin M Cleary
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, United States
| | - Ian C Wenker
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, United States
| | - Todd Dubreuil
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, United States
| | - Elliot M Rodriguez
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, United States
| | - Mark T Nelson
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, United States.,Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, United States
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Samarage CR, Carnibella R, Preissner M, Jones HD, Pearson JT, Fouras A, Dubsky S. Technical Note: Contrast free angiography of the pulmonary vasculature in live mice using a laboratory x-ray source. Med Phys 2017; 43:6017. [PMID: 27806595 PMCID: PMC5074996 DOI: 10.1118/1.4964794] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose: In vivo imaging of the pulmonary vasculature in small animals is difficult yet highly desirable in order to allow study of the effects of a host of dynamic biological processes such as hypoxic pulmonary vasoconstriction. Here the authors present an approach for the quantification of changes in the vasculature. Methods: A contrast free angiography technique is validated in silico through the use of computer-generated images and in vivo through microcomputed tomography (μCT) of live mice conducted using a laboratory-based x-ray source. Subsequent image processing on μCT data allowed for the quantification of the caliber of pulmonary vasculature without the need for external contrast agents. These measures were validated by comparing with quantitative contrast microangiography in the same mice. Results: Quantification of arterial diameters from the method proposed in this study is validated against laboratory-based x-ray contrast microangiography. The authors find that there is a high degree of correlation (R = 0.91) between measures from microangiography and their contrast free method. Conclusions: A technique for quantification of murine pulmonary vasculature without the need for contrast is presented. As such, this technique could be applied for longitudinal studies of animals to study changes to vasculature without the risk of premature death in sensitive mouse models of disease. This approach may also be of value in the clinical setting.
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Affiliation(s)
| | - Richard Carnibella
- 4Dx Limited, Melbourne 3000, Australia and Department of Mechanical and Aerospace Engineering, Monash University, Melbourne 3800, Australia
| | - Melissa Preissner
- Department of Mechanical and Aerospace Engineering, Monash University, Melbourne 3800, Australia
| | - Heather D Jones
- Department of Medicine and the Women's Guild Lung Institute, Cedars-Sinai Medical Center, Los Angeles, California 90048
| | - James T Pearson
- Department of Physiology, Monash University, Melbourne 3800, Australia; Monash Biomedical Imaging Facility Monash University, Melbourne 3800, Australia; and Australian Synchrotron, Melbourne 3168, Australia
| | - Andreas Fouras
- 4Dx Limited, Melbourne 3000, Australia and Department of Mechanical and Aerospace Engineering, Monash University, Melbourne 3800, Australia
| | - Stephen Dubsky
- 4Dx Limited, Melbourne 3000, Australia and Department of Mechanical and Aerospace Engineering, Monash University, Melbourne 3800, Australia
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van der Putten MA, MacKenzie LE, Davies AL, Fernandez-Ramos J, Desai RA, Smith KJ, Harvey AR. A multispectral microscope for in vivo oximetry of rat dorsal spinal cord vasculature. Physiol Meas 2016; 38:205-218. [PMID: 28001129 DOI: 10.1088/1361-6579/aa5527] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Quantification of blood oxygen saturation (SO2) in vivo is essential for understanding the pathogenesis of diseases in which hypoxia is thought to play a role, including inflammatory disorders such as multiple sclerosis (MS) and rheumatoid arthritis (RA). We describe a low-cost multispectral microscope and oximetry technique for calibration-free absolute oximetry of surgically exposed blood vessels in vivo. We imaged the vasculature of the dorsal spinal cord in healthy rats, and varied inspired oxygen (FiO2) in order to evaluate the sensitivity of the imaging system to changes in SO2. The venous SO2 was calculated as 67.8 ± 10.4% (average ± standard deviation), increasing to 83.1 ± 11.6% under hyperoxic conditions (100% FiO2) and returning to 67.4 ± 10.9% for a second normoxic period; the venous SO2 was 50.9 ± 15.5% and 29.2 ± 24.6% during subsequent hypoxic states (18% and 15% FiO2 respectively). We discuss the design and performance of our multispectral imaging system, and the future scope for extending this oximetry technique to quantification of hypoxia in inflamed tissue.
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45
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Desai M, Slusarczyk AL, Chapin A, Barch M, Jasanoff A. Molecular imaging with engineered physiology. Nat Commun 2016; 7:13607. [PMID: 27910951 PMCID: PMC5146284 DOI: 10.1038/ncomms13607] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 10/19/2016] [Indexed: 12/30/2022] Open
Abstract
In vivo imaging techniques are powerful tools for evaluating biological systems. Relating image signals to precise molecular phenomena can be challenging, however, due to limitations of the existing optical, magnetic and radioactive imaging probe mechanisms. Here we demonstrate a concept for molecular imaging which bypasses the need for conventional imaging agents by perturbing the endogenous multimodal contrast provided by the vasculature. Variants of the calcitonin gene-related peptide artificially activate vasodilation pathways in rat brain and induce contrast changes that are readily measured by optical and magnetic resonance imaging. CGRP-based agents induce effects at nanomolar concentrations in deep tissue and can be engineered into switchable analyte-dependent forms and genetically encoded reporters suitable for molecular imaging or cell tracking. Such artificially engineered physiological changes, therefore, provide a highly versatile means for sensitive analysis of molecular events in living organisms.
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Affiliation(s)
- Mitul Desai
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 16-561, Cambridge, Massachusetts 02139, USA
| | - Adrian L. Slusarczyk
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 16-561, Cambridge, Massachusetts 02139, USA
| | - Ashley Chapin
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 16-561, Cambridge, Massachusetts 02139, USA
| | - Mariya Barch
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 16-561, Cambridge, Massachusetts 02139, USA
| | - Alan Jasanoff
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 16-561, Cambridge, Massachusetts 02139, USA
- Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 16-561, Cambridge, Massachusetts 02139, USA
- Department of Nuclear Science & Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 16-561, Cambridge, Massachusetts 02139, USA
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46
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Negrini D, Marcozzi C, Solari E, Bossi E, Cinquetti R, Reguzzoni M, Moriondo A. Hyperpolarization-activated cyclic nucleotide-gated channels in peripheral diaphragmatic lymphatics. Am J Physiol Heart Circ Physiol 2016; 311:H892-H903. [DOI: 10.1152/ajpheart.00193.2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 08/01/2016] [Indexed: 11/22/2022]
Abstract
Diaphragmatic lymphatic function is mainly sustained by pressure changes in the tissue and serosal cavities during cardiorespiratory cycles. The most peripheral diaphragmatic lymphatics are equipped with muscle cells (LMCs), which exhibit spontaneous contraction, whose molecular machinery is still undetermined. Hypothesizing that spontaneous contraction might involve hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in lymphatic LMCs, diaphragmatic specimens, including spontaneously contracting lymphatics, were excised from 33 anesthetized rats, moved to a perfusion chamber containing HEPES-Tyrode's solution, and treated with HCN channels inhibitors cesium chloride (CsCl), ivabradine, and ZD-7288. Compared with control, exposure to 10 mM CsCl reduced (−65%, n = 13, P < 0.01) the contraction frequency (FL) and increased end-diastolic diameter (DL-d, +7.3%, P < 0.01) without changes in end-systolic diameter (DL-s). Ivabradine (300 μM) abolished contraction and increased DL-d (−14%, n = 10, P < 0.01) or caused an incomplete inhibition of FL ( n = 3, P < 0.01), leaving DL-d and DL-s unaltered. ZD-7288 (200 μM) completely ( n = 12, P < 0.01) abolished FL, while DL-d decreased to 90.9 ± 2.7% of control. HCN gene expression and immunostaining confirmed the presence of HCN1-4 channel isoforms, likely arranged in different configurations, in LMCs. Hence, all together, data suggest that HCN channels might play an important role in affecting contraction frequency of LMCs.
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Affiliation(s)
- Daniela Negrini
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and
| | - Cristiana Marcozzi
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and
| | - Eleonora Solari
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and
| | - Elena Bossi
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Raffaella Cinquetti
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Marcella Reguzzoni
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and
| | - Andrea Moriondo
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and
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Phan TX, Ton HT, Chen Y, Basha ME, Ahern GP. Sex-dependent expression of TRPV1 in bladder arterioles. Am J Physiol Renal Physiol 2016; 311:F1063-F1073. [PMID: 27654891 DOI: 10.1152/ajprenal.00234.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 09/18/2016] [Indexed: 12/30/2022] Open
Abstract
Transient receptor potential vanilloid type 1 (TRPV1) is a major nociceptive ion channel implicated in bladder physiology and/or pathophysiology. However, the precise expression of TRPV1 in neuronal vs. nonneuronal bladder cells is uncertain. Here we used reporter mouse lines (TRPV1-Cre:tdTomato and TRPV1PLAP-nlacZ) to map expression of TRPV1 in postnatal bladder. TRPV1 was not detected in the urothelium, however, we found marked expression of TRPV1 lineage in sensory nerves, and surprisingly, in arterial/arteriolar smooth muscle (ASM) cells. Tomato fluorescence was prominent in the vesical arteries and in small-diameter (15-40 μm) arterioles located in the suburothelial layer with a near equal distribution in bladder dome and base. Notably, arteriolar TRPV1 expression was greater in females than in males and increased in both sexes after 90 days of age, suggesting sex hormone and age dependency. Analysis of whole bladder and vesical artery TRPV1 mRNA revealed a similar sex and developmental dependence. Pharmacological experiments confirmed functional TRPV1 protein expression; capsaicin increased intracellular Ca2+ in ∼15% of ASM cells from wild-type female bladders, but we observed no responses to capsaicin in bladder arterioles isolated from TRPV1-null mice. Furthermore, capsaicin triggered arteriole constriction that was rapidly reversed by the TRPV1 antagonist, BCTC. These data show that predominantly in postpubertal female mice, bladder ASM cells express functional TRPV1 channels that may act to constrict arterioles. TRPV1 may therefore play an important role in regulating the microcirculation of the female bladder, and this effect may be of significance during inflammatory conditions.
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Affiliation(s)
- Thieu X Phan
- Department of Pharmacology & Physiology, Georgetown University, Washington, DC.,Department of Biology, Vinh University, Vinh City, Vietnam; and
| | - Hoai T Ton
- Department of Pharmacology & Physiology, Georgetown University, Washington, DC.,Department of Biology, Vinh University, Vinh City, Vietnam; and
| | - Yue Chen
- Department of Pharmacology & Physiology, Georgetown University, Washington, DC
| | - Maureen E Basha
- Department of Biomedical Sciences, West Virginia School of Osteopathic Medicine, Lewisburg, West Virginia
| | - Gerard P Ahern
- Department of Pharmacology & Physiology, Georgetown University, Washington, DC;
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Endothelin-1 Treatment Induces an Experimental Cerebral Malaria-Like Syndrome in C57BL/6 Mice Infected with Plasmodium berghei NK65. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:2957-2969. [PMID: 27640146 DOI: 10.1016/j.ajpath.2016.07.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Revised: 06/06/2016] [Accepted: 07/11/2016] [Indexed: 12/22/2022]
Abstract
Plasmodium berghei ANKA infection of C57BL/6 mice is a widely used model of experimental cerebral malaria (ECM). By contrast, the nonneurotropic P. berghei NK65 (PbN) causes severe malarial disease in C57BL/6 mice but does not cause ECM. Previous studies suggest that endothelin-1 (ET-1) contributes to the pathogenesis of ECM. In this study, we characterize the role of ET-1 on ECM vascular dysfunction. Mice infected with 106 PbN-parasitized red blood cells were treated with either ET-1 or saline from 2 to 8 days postinfection (dpi). Plasmodium berghei ANKA-infected mice served as the positive control. ET-1-treated PbN-infected mice exhibited neurological signs, hypothermia, and behavioral alterations characteristic of ECM, dying 4 to 8 dpi. Parasitemia was not affected by ET-1 treatment. Saline-treated PbN-infected mice did not display ECM, surviving until 12 dpi. ET-1-treated PbN-infected mice displayed leukocyte adhesion to the vascular endothelia and petechial hemorrhages throughout the brain at 6 dpi. Intravital microscopic images demonstrated significant brain arteriolar vessel constriction, decreased functional capillary density, and increased blood-brain barrier permeability. These alterations were not present in either ET-1-treated uninfected or saline-treated PbN-infected mice. In summary, ET-1 treatment of PbN-infected mice induced an ECM-like syndrome, causing brain vasoconstriction, adherence of activated leukocytes in the cerebral microvasculature, and blood-brain barrier leakage, indicating that ET-1 is involved in the genesis of brain microvascular alterations that are the hallmark of ECM.
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Evidence of Flicker-Induced Functional Hyperaemia in the Smallest Vessels of the Human Retinal Blood Supply. PLoS One 2016; 11:e0162621. [PMID: 27617960 PMCID: PMC5019460 DOI: 10.1371/journal.pone.0162621] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/25/2016] [Indexed: 12/02/2022] Open
Abstract
Regional changes in blood flow are initiated within neural tissue to help fuel local differences in neural activity. Classically, this response was thought to arise only in larger arterioles and venules. However, recently, it has been proposed that a) the smallest vessels of the circulation make a comparable contribution, and b) the response should be localised intermittently along such vessels, due to the known distribution of contractile mural cells. To assess these hypotheses in human neural tissue in vivo, we imaged the retinal microvasculature (diameters 3–28 μm) non-invasively, using adaptive optics, before and after delivery of focal (360 μm) patches of flickering visible light. Our results demonstrated a definite average response in 35% of all vessel segments analysed. In these responding vessels, the magnitude of proportional dilation (mean ± SEM for pre-capillary arterioles 13 ± 5%, capillaries 31 ± 8%, and post-capillary venules 10 ± 3%) is generally far greater than the magnitudes we and others have measured in the larger retinal vessels, supporting proposition a) above. The dilations observed in venules were unexpected based on previous animal work, and may be attributed either to differences in stimulus or species. Response heterogeneity across the network was high; responses were also heterogeneous along individual vessels (45% of vessel segments showed demonstrable locality in their response). These observations support proposition b) above. We also observed a definite average constriction across 7% of vessel segments (mean ± SEM constriction for capillaries -16 ± 3.2%, and post-capillary venules -18 ± 12%), which paints a picture of dynamic redistribution of flow throughout the smallest vessel networks in the retina in response to local, stimulus-driven metabolic demand.
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50
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Rezaeian M, Georgevsky D, Golzan SM, Graham SL. High speed in-vivo imaging of retinal hemodynamics in a rodent model of hypertension. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2016:3243-3246. [PMID: 28268999 DOI: 10.1109/embc.2016.7591420] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The eye is the only organ through which microcirculation can be visualized non-invasively. This unique feature makes the eye and specifically retinal vasculature an excellent target area to monitor and study micro-vascular damage in systemic diseases. Dynamic (real-time) changes of retinal vessels have been shown to be more specific to the disease in comparison with static measurements. In this study we utilize high speed imaging (i.e. 125 fps) to study and derive dynamic changes of retinal vessels in a rat model of hypertension. A Eulerian video magnification algorithm was used to extract retinal arterial and venous pulse amplitude from five Spontaneously Hypertensive Rats (SHR) and five Wister Kyoto (WKY) rats were used as the control group. Results showed that retinal arterial diameter and pulse amplitude are significantly lower in the SHRs compared with WKYs. Dynamic biomarkers of retinal micro-vasculature may be used as a diagnostic tool for systemic diseases.
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