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Wood N, Straw S, Cheng CW, Hirata Y, Pereira MG, Gallagher H, Egginton S, Ogawa W, Wheatcroft SB, Witte KK, Roberts LD, Bowen TS. Sodium-glucose cotransporter 2 inhibitors influence skeletal muscle pathology in patients with heart failure and reduced ejection fraction. Eur J Heart Fail 2024. [PMID: 38468429 DOI: 10.1002/ejhf.3192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/12/2024] [Accepted: 02/23/2024] [Indexed: 03/13/2024] Open
Abstract
AIMS Patients with heart failure and reduced ejection fraction (HFrEF) exhibit skeletal muscle pathology, which contributes to symptoms and decreased quality of life. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) improve clinical outcomes in HFrEF but their mechanism of action remains poorly understood. We aimed, therefore, to determine whether SGLT2i influence skeletal muscle pathology in patients with HFrEF. METHODS AND RESULTS Muscle biopsies from 28 male patients with HFrEF (New York Heart association class I-III) treated with SGLT2i (>12 months) or without SGLT2i were compared. Comprehensive analyses of muscle structure (immunohistochemistry), transcriptome (RNA sequencing), and metabolome (liquid chromatography-mass spectrometry) were performed, and serum inflammatory profiling (ELISA). Experiments in mice (n = 16) treated with SGLT2i were also performed. Myofiber atrophy was ~20% less in patients taking SGLT2i (p = 0.07). Transcriptomics and follow-up measures identified a unique signature in patients taking SGLT2i related to beneficial effects on atrophy, metabolism, and inflammation. Metabolomics identified influenced tryptophan metabolism in patients taking SGLT2i: kynurenic acid was 24% higher and kynurenine was 32% lower (p < 0.001). Serum profiling identified that SGLT2i treatment was associated with lower (p < 0.05) pro-inflammatory cytokines by 26-64% alongside downstream muscle interleukin (IL)-6-JAK/STAT3 signalling (p = 008 and 0.09). Serum IL-6 and muscle kynurenine were correlated (R = 0.65; p < 0.05). Muscle pathology was lower in mice treated with SGLT2i indicative of a conserved mammalian response to treatment. CONCLUSIONS Treatment with SGLT2i influenced skeletal muscle pathology in patients with HFrEF and was associated with anti-atrophic, anti-inflammatory, and pro-metabolic effects. These changes may be regulated via IL-6-kynurenine signalling. Together, clinical improvements following SGLT2i treatment in patients with HFrEF may be partly explained by their positive effects on skeletal muscle pathology.
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Affiliation(s)
- Nathanael Wood
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Sam Straw
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Chew W Cheng
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Yu Hirata
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Marcelo G Pereira
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Harrison Gallagher
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Wataru Ogawa
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Stephen B Wheatcroft
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Klaus K Witte
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
- Clinic for Cardiology, Angiology and Internal Intensive Care Medicine, RWTH Aachen University, Aachen, Germany
| | - Lee D Roberts
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - T Scott Bowen
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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Espino-Gonzalez E, Tickle PG, Altara R, Booz GW, Cataliotti A, Roberts LD, Egginton S, Bowen TS. Reply: Navigating Nutritional Nuances in the Research of Heart Failure With Preserved Ejection Fraction. JACC Basic Transl Sci 2024; 9:403. [PMID: 38559617 PMCID: PMC10978390 DOI: 10.1016/j.jacbts.2024.01.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Affiliation(s)
| | | | - Raffaele Altara
- Maastricht University, Maastricht, the Netherlands
- University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - George W. Booz
- University of Mississippi Medical Center, Jackson, Mississippi, USA
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Espino-Gonzalez E, Tickle PG, Altara R, Gallagher H, Cheng CW, Engman V, Wood N, Justo da Silva GJ, Scalabrin M, Yu X, Zhong Z, Colman MA, Yuldasheva NY, Booz GW, Adams V, Pereira MG, Cataliotti A, Roberts LD, Egginton S, Bowen TS. Caloric Restriction Rejuvenates Skeletal Muscle Growth in Heart Failure With Preserved Ejection Fraction. JACC Basic Transl Sci 2024; 9:223-240. [PMID: 38510717 PMCID: PMC10950401 DOI: 10.1016/j.jacbts.2023.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 03/22/2024]
Abstract
Heart failure with preserved ejection fraction (HFpEF) is a major clinical problem, with limited treatments. HFpEF is characterized by a distinct, but poorly understood, skeletal muscle pathology, which could offer an alternative therapeutic target. In a rat model, we identified impaired myonuclear accretion as a mechanism for low myofiber growth in HFpEF following resistance exercise. Acute caloric restriction rescued skeletal muscle pathology in HFpEF, whereas cardiac therapies had no effect. Mechanisms regulating myonuclear accretion were dysregulated in patients with HFpEF. Overall, these findings may have widespread implications in HFpEF, indicating combined dietary with exercise interventions as a beneficial approach to overcome skeletal muscle pathology.
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Affiliation(s)
- Ever Espino-Gonzalez
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Peter G. Tickle
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Raffaele Altara
- Department of Anatomy & Embryology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands
- Department of Pathology, School of Medicine, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Harrison Gallagher
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Chew W. Cheng
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine, University of Leeds, Leeds, United Kingdom
| | - Viktor Engman
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Nathanael Wood
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | | | - Mattia Scalabrin
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Xinyue Yu
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Ziyi Zhong
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Michael A. Colman
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Nadira Y. Yuldasheva
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine, University of Leeds, Leeds, United Kingdom
| | - George W. Booz
- Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Volker Adams
- Heart Center Dresden, TU-Dresden, Dresden, Germany
| | - Marcelo G. Pereira
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Alessandro Cataliotti
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Lee D. Roberts
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine, University of Leeds, Leeds, United Kingdom
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - T. Scott Bowen
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
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4
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Gilmour KM, Daley MA, Egginton S, Kelber A, McHenry MJ, Patek SN, Sane SP, Schulte PM, Terblanche JS, Wright PA, Franklin CE. Through the looking glass: attempting to predict future opportunities and challenges in experimental biology. J Exp Biol 2023; 226:jeb246921. [PMID: 38059428 DOI: 10.1242/jeb.246921] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
To celebrate its centenary year, Journal of Experimental Biology (JEB) commissioned a collection of articles examining the past, present and future of experimental biology. This Commentary closes the collection by considering the important research opportunities and challenges that await us in the future. We expect that researchers will harness the power of technological advances, such as '-omics' and gene editing, to probe resistance and resilience to environmental change as well as other organismal responses. The capacity to handle large data sets will allow high-resolution data to be collected for individual animals and to understand population, species and community responses. The availability of large data sets will also place greater emphasis on approaches such as modeling and simulations. Finally, the increasing sophistication of biologgers will allow more comprehensive data to be collected for individual animals in the wild. Collectively, these approaches will provide an unprecedented understanding of 'how animals work' as well as keys to safeguarding animals at a time when anthropogenic activities are degrading the natural environment.
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Affiliation(s)
| | - Monica A Daley
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Almut Kelber
- Department of Biology, Lund University, 22362 Lund, Sweden
| | - Matthew J McHenry
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Sheila N Patek
- Biology Department, Duke University, Durham, NC 27708, USA
| | - Sanjay P Sane
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bellary Road, Bangalore, Karnataka 560065, India
| | - Patricia M Schulte
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - John S Terblanche
- Center for Invasion Biology, Department of Conservation Ecology & Entomology, Stellenbosch University, Stellenbosch 7602, South Africa
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Craig E Franklin
- School of the Environment, The University of Queensland, St. Lucia, Brisbane 4072, Australia
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5
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Kissane RWP, Hauton D, Tickle PG, Egginton S. Skeletal muscle adaptation to indirect electrical stimulation: divergence between microvascular and metabolic adaptations. Exp Physiol 2023; 108:891-911. [PMID: 37026596 PMCID: PMC10988499 DOI: 10.1113/ep091134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 03/15/2023] [Indexed: 04/08/2023]
Abstract
NEW FINDINGS What is the central question of this study? Can we manipulate muscle recruitment to differentially enhance skeletal muscle fatigue resistance? What is the main finding and its importance? Through manipulation of muscle activation patterns, it is possible to promote distinct microvascular growth. Enhancement of fatigue resistance is closely associated with the distribution of the capillaries within the muscle, not necessarily with quantity. Additionally, at the acute stages of remodelling in response to indirect electrical stimulation, the improvement in fatigue resistance appears to be primarily driven by vascular remodelling, with metabolic adaptation of secondary importance. ABSTRACT Exercise involves a complex interaction of factors influencing muscle performance, where variations in recruitment pattern (e.g., endurance vs. resistance training) may differentially modulate the local tissue environment (i.e., oxygenation, blood flow, fuel utilization). These exercise stimuli are potent drivers of vascular and metabolic change. However, their relative contribution to adaptive remodelling of skeletal muscle and subsequent performance is unclear. Using implantable devices, indirect electrical stimulation (ES) of locomotor muscles of rat at different pacing frequencies (4, 10 and 40 Hz) was used to differentially recruit hindlimb blood flow and modulate fuel utilization. After 7 days, ES promoted significant remodelling of microvascular composition, increasing capillary density in the cortex of the tibialis anterior by 73%, 110% and 55% for the 4 Hz, 10 and 40 Hz groups, respectively. Additionally, there was remodelling of the whole muscle metabolome, including significantly elevated amino acid turnover, with muscle kynurenic acid levels doubled by pacing at 10 Hz (P < 0.05). Interestingly, the fatigue index of skeletal muscle was only significantly elevated in 10 Hz (58% increase) and 40 Hz (73% increase) ES groups, apparently linked to improved capillary distribution. These data demonstrate that manipulation of muscle recruitment pattern may be used to differentially expand the capillary network prior to altering the metabolome, emphasising the importance of local capillary supply in promoting exercise tolerance.
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Affiliation(s)
- Roger W. P. Kissane
- Department of Musculoskeletal & Ageing Science, Faculty of Health & Life SciencesUniversity of LiverpoolLiverpoolUK
- School of Biomedical Sciences, Faculty of BiosciencesUniversity of LeedsLeedsUK
| | - David Hauton
- Metabolomics Research Group, Department of ChemistryUniversity of OxfordOxfordUK
| | - Peter G. Tickle
- School of Biomedical Sciences, Faculty of BiosciencesUniversity of LeedsLeedsUK
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of BiosciencesUniversity of LeedsLeedsUK
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6
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Smith NJ, Doody NE, Štěpánková K, Fuller M, Ichiyama RM, Kwok JCF, Egginton S. Spatiotemporal microvascular changes following contusive spinal cord injury. Front Neuroanat 2023; 17:1152131. [PMID: 37025098 PMCID: PMC10070689 DOI: 10.3389/fnana.2023.1152131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 02/27/2023] [Indexed: 04/08/2023] Open
Abstract
Microvascular integrity is disrupted following spinal cord injury (SCI) by both primary and secondary insults. Changes to neuronal structures are well documented, but little is known about how the capillaries change and recover following injury. Spatiotemporal morphological information is required to explore potential treatments targeting the microvasculature post-SCI to improve functional recovery. Sprague-Dawley rats were given a T10 moderate/severe (200 kDyn) contusion injury and were perfuse-fixed at days 2, 5, 15, and 45 post-injury. Unbiased stereology following immunohistochemistry in four areas (ventral and dorsal grey and white matter) across seven spinal segments (n = 4 for each group) was used to calculate microvessel density, surface area, and areal density. In intact sham spinal cords, average microvessel density across the thoracic spinal cord was: ventral grey matter: 571 ± 45 mm-2, dorsal grey matter: 484 ± 33 mm-2, ventral white matter: 90 ± 8 mm-2, dorsal white matter: 88 ± 7 mm-2. Post-SCI, acute microvascular disruption was evident, particularly at the injury epicentre, and spreading three spinal segments rostrally and caudally. Damage was most severe in grey matter at the injury epicentre (T10) and T11. Reductions in all morphological parameters (95-99% at day 2 post-SCI) implied vessel regression and/or collapse acutely. Transmission electron microscopy (TEM) revealed disturbed aspects of neurovascular unit fine structure at day 2 post-SCI (n = 2 per group) at T10 and T11. TEM demonstrated a more diffuse and disrupted basement membrane and wider intercellular clefts at day 2, suggesting a more permeable blood spinal cord barrier and microvessel remodelling. Some evidence of angiogenesis was seen during recovery from days 2 to 45, indicated by increased vessel density, surface area, and areal density at day 45. These novel results show that the spinal cord microvasculature is highly adaptive following SCI, even at chronic stages and up to three spinal segments from the injury epicentre. Multiple measures of gross and fine capillary structure from acute to chronic time points provide insight into microvascular remodelling post-SCI. We have identified key vascular treatment targets, namely stabilising damaged capillaries and replacing destroyed vessels, which may be used to improve functional outcomes following SCI in the future.
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Affiliation(s)
- Nicole J. Smith
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Natalie E. Doody
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Kateřina Štěpánková
- Centre for Reconstructive Neuroscience, Czech Academy of Sciences, Prague, Czechia
- Department of Neuroscience, Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Martin Fuller
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | | | - Jessica C. F. Kwok
- Centre for Reconstructive Neuroscience, Czech Academy of Sciences, Prague, Czechia
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
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7
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Affiliation(s)
- Roger Kissane
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
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8
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Kissane RWP, Chakrabarty S, Askew GN, Egginton S. Heterogeneity in form and function of the rat extensor digitorum longus motor unit. J Anat 2021; 240:700-710. [PMID: 34761377 PMCID: PMC8930811 DOI: 10.1111/joa.13590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 11/01/2021] [Accepted: 11/01/2021] [Indexed: 11/29/2022] Open
Abstract
The motor unit comprises a variable number of muscle fibres that connect through myelinated nerve fibres to a motoneuron (MN), the central drivers of activity. At the simplest level of organisation there exist phenotypically distinct MNs that activate corresponding muscle fibre types, but within an individual motor pool there typically exists a mixed population of fast and slow firing MNs, innervating groups of Type II and Type I fibres, respectively. Characterising the heterogeneity across multiple levels of motor unit organisation is critical to understanding changes that occur in response to physiological and pathological perturbations. Through a comprehensive assessment of muscle histology and ex vivo function, mathematical modelling and neuronal tracing, we demonstrate regional heterogeneities at the level of the MN, muscle fibre type composition and oxygen delivery kinetics of the rat extensor digitorum longus (EDL) muscle. Specifically, the EDL contains two phenotypically distinct regions: a relatively oxidative medial and a more glycolytic lateral compartment. Smaller muscle fibres in the medial compartment, in combination with a greater local capillary density, preserve tissue O2 partial pressure (PO2) during modelled activity. Conversely, capillary supply to the lateral compartment is calculated to be insufficient to defend active muscle PO2 but is likely optimised to facilitate metabolite removal. Simulation of in vivo muscle length change and phasic activation suggest that both compartments are able to generate similar net power. However, retrograde tracing demonstrates (counter to previous observations) that a negative relationship between soma size and C‐bouton density exists. Finally, we confirm a lack of specificity of SK3 expression to slow MNs. Together, these data provide a reference for heterogeneities across the rat EDL motor unit and re‐emphasise the importance of sampling technique.
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Affiliation(s)
- Roger W P Kissane
- Department of Musculoskeletal & Ageing Science, University of Liverpool, Liverpool, UK
| | | | - Graham N Askew
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds, UK
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Sissaoui S, Egginton S, Ting L, Ahmed A, Hewett PW. Hyperglycaemia up-regulates placental growth factor (PlGF) expression and secretion in endothelial cells via suppression of PI3 kinase-Akt signalling and activation of FOXO1. Sci Rep 2021; 11:16344. [PMID: 34381074 PMCID: PMC8357836 DOI: 10.1038/s41598-021-95511-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 07/13/2021] [Indexed: 01/13/2023] Open
Abstract
Placenta growth factor (PlGF) is a pro-inflammatory angiogenic mediator that promotes many pathologies including diabetic complications and atherosclerosis. Widespread endothelial dysfunction precedes the onset of these conditions. As very little is known of the mechanism(s) controlling PlGF expression in pathology we investigated the role of hyperglycaemia in the regulation of PlGF production in endothelial cells. Hyperglycaemia stimulated PlGF secretion in cultured primary endothelial cells, which was suppressed by IGF-1-mediated PI3K/Akt activation. Inhibition of PI3K activity resulted in significant PlGF mRNA up-regulation and protein secretion. Similarly, loss or inhibition of Akt activity significantly increased basal PlGF expression and prevented any further PlGF secretion in hyperglycaemia. Conversely, constitutive Akt activation blocked PlGF secretion irrespective of upstream PI3K activity demonstrating that Akt is a central regulator of PlGF expression. Knock-down of the Forkhead box O-1 (FOXO1) transcription factor, which is negatively regulated by Akt, suppressed both basal and hyperglycaemia-induced PlGF secretion, whilst FOXO1 gain-of-function up-regulated PlGF in vitro and in vivo. FOXO1 association to a FOXO binding sequence identified in the PlGF promoter also increased in hyperglycaemia. This study identifies the PI3K/Akt/FOXO1 signalling axis as a key regulator of PlGF expression and unifying pathway by which PlGF may contribute to common disorders characterised by endothelial dysfunction, providing a target for therapy.
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Affiliation(s)
- Samir Sissaoui
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Arima Genomics, 6404 Nancy Ridge Drive, San Diego, CA, 92121, USA
| | - Stuart Egginton
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, LS2 9JT, UK
| | - Ling Ting
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Asif Ahmed
- MyrZyme Therapeutics Ltd, Faraday Wharf, Innovation Birmingham Campus, Holt Street, Birmingham, B4 4BB, UK
- School of Health Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - Peter W Hewett
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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Tickle PG, Hendrickse PW, Weightman A, Nazir MH, Degens H, Egginton S. Impaired skeletal muscle fatigue resistance during cardiac hypertrophy is prevented by functional overload- or exercise-induced functional capillarity. J Physiol 2021; 599:3715-3733. [PMID: 34107075 DOI: 10.1113/jp281377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Accepted: 06/04/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Capillary rarefaction is hypothesized to contribute to impaired exercise tolerance in cardiovascular disease, but it remains a poorly exploited therapeutic target for improving skeletal muscle performance. Using an abdominal aortic coarctation rat model of compensatory cardiac hypertrophy, we determine the efficacy of aerobic exercise for the prevention of, and mechanical overload for, restoration of hindlimb muscle fatigue resistance and microvascular impairment in the early stages of heart disease. Impaired muscle fatigue resistance was found after development of cardiac hypertrophy, but this impairment was prevented by low-intensity aerobic exercise and recovered after mechanical stretch due to muscle overload. Changes in muscle fatigue resistance were closely related to functional (i.e. perfused) microvascular density, independent of arterial blood flow, emphasizing the critical importance of optimal capillary diffusion for skeletal muscle function. Pro-angiogenic therapies are an important tool for improving skeletal muscle function in the incipient stages of heart disease. ABSTRACT Microvascular rarefaction may contribute to declining skeletal muscle performance in cardiac and vascular diseases. It remains uncertain to what extent microvascular rarefaction occurs in the earliest stages of these conditions, if impaired blood flow is an aggravating factor and whether angiogenesis restores muscle performance. To investigate this, the effects of aerobic exercise (voluntary wheel running) and functional muscle overload on the performance, femoral blood flow (FBF) and microvascular perfusion of the extensor digitorum longus (EDL) were determined in a chronic rat model of compensatory cardiac hypertrophy (CCH, induced by surgically imposed abdominal aortic coarctation). CCH was associated with hypertension (P = 0.001 vs. Control) and increased relative heart mass (P < 0.001). Immediately upon placing the aortic band (i.e. before development of CCH), post-fatigue test FBF was reduced (P < 0.003), coinciding with attenuated fatigue resistance (P = 0.039) indicating an acute arterial perfusion constraint on muscle performance. While FBF was normalized during CCH in chronic groups (P > 0.05) fatigue resistance remained reduced (P = 0.039) and was associated with reduced (P = 0.009) functional capillarity after development of CCH without intervention, indicating a microvascular limitation to muscle performance. Normalization of functional capillarity after aerobic exercise (P = 0.065) and overload (P = 0.329) in CCH coincided with restoration to control levels of muscle fatigue resistance (P > 0.999), although overload-induced EDL hypertrophy (P = 0.027) and wheel-running velocity and duration (both P < 0.05) were attenuated after aortic banding. These data show that reductions in skeletal muscle performance during CCH can be countered by improving functional capillarity, providing a therapeutic target to improve skeletal muscle function in chronic diseases.
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Affiliation(s)
- Peter G Tickle
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Paul W Hendrickse
- Department of Life Sciences, Research Centre for Musculoskeletal Science & Sports Medicine, Manchester Metropolitan University, Manchester, UK.,Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Andrew Weightman
- Department of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester, UK
| | - M Hakam Nazir
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Hans Degens
- Department of Life Sciences, Research Centre for Musculoskeletal Science & Sports Medicine, Manchester Metropolitan University, Manchester, UK.,Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds, UK
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11
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O'Brien KM, Joyce W, Crockett EL, Axelsson M, Egginton S, Farrell AP. Resilience of cardiac performance in Antarctic notothenioid fishes in a warming climate. J Exp Biol 2021; 224:268390. [PMID: 34042975 DOI: 10.1242/jeb.220129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Warming in the region of the Western Antarctic Peninsula is occurring at an unprecedented rate, which may threaten the survival of Antarctic notothenioid fishes. Herein, we review studies characterizing thermal tolerance and cardiac performance in notothenioids - a group that includes both red-blooded species and the white-blooded, haemoglobinless icefishes - as well as the relevant biochemistry associated with cardiac failure during an acute temperature ramp. Because icefishes do not feed in captivity, making long-term acclimation studies unfeasible, we focus only on the responses of red-blooded notothenioids to warm acclimation. With acute warming, hearts of the white-blooded icefish Chaenocephalus aceratus display persistent arrhythmia at a lower temperature (8°C) compared with those of the red-blooded Notothenia coriiceps (14°C). When compared with the icefish, the enhanced cardiac performance of N. coriiceps during warming is associated with greater aerobic capacity, higher ATP levels, less oxidative damage and enhanced membrane integrity. Cardiac performance can be improved in N. coriiceps with warm acclimation to 5°C for 6-9 weeks, accompanied by an increase in the temperature at which cardiac failure occurs. Also, both cardiac mitochondrial and microsomal membranes are remodelled in response to warm acclimation in N. coriiceps, displaying homeoviscous adaptation. Overall, cardiac performance in N. coriiceps is malleable and resilient to warming, yet thermal tolerance and plasticity vary among different species of notothenioid fishes; disruptions to the Antarctic ecosystem driven by climate warming and other anthropogenic activities endanger the survival of notothenioids, warranting greater protection afforded by an expansion of marine protected areas.
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Affiliation(s)
- Kristin M O'Brien
- Institute of Arctic Biology , University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA
| | - William Joyce
- Department of Biology - Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark
| | | | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Stuart Egginton
- School of Biomedical Sciences , University of Leeds, Leeds LS2 9JT, UK
| | - Anthony P Farrell
- Department of Zoology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
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12
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Kissane RWP, Ghaffari-Rafi A, Tickle PG, Chakrabarty S, Egginton S, Brownstone RM, Smith CC. C-bouton components on rat extensor digitorum longus motoneurons are resistant to chronic functional overload. J Anat 2021; 241:1157-1168. [PMID: 33939175 PMCID: PMC9558151 DOI: 10.1111/joa.13439] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/17/2021] [Accepted: 03/18/2021] [Indexed: 02/06/2023] Open
Abstract
Mammalian motor systems adapt to the demands of their environment. For example, muscle fibre types change in response to increased load or endurance demands. However, for adaptations to be effective, motoneurons must adapt such that their properties match those of the innervated muscle fibres. We used a rat model of chronic functional overload to assess adaptations to both motoneuron size and a key modulatory synapse responsible for amplification of motor output, C‐boutons. Overload of extensor digitorum longus (EDL) muscles was induced by removal of their synergists, tibialis anterior muscles. Following 21 days survival, EDL muscles showed an increase in fatigue resistance and a decrease in force output, indicating a shift to a slower phenotype. These changes were reflected by a decrease in motoneuron size. However, C‐bouton complexes remained largely unaffected by overload. The C‐boutons themselves, quantified by expression of vesicular acetylcholine transporter, were similar in size and density in the control and overload conditions. Expression of the post‐synaptic voltage‐gated potassium channel (KV2.1) was also unchanged. Small conductance calcium‐activated potassium channels (SK3) were expressed in most EDL motoneurons, despite this being an almost exclusively fast motor pool. Overload induced a decrease in the proportion of SK3+ cells, however, there was no change in density or size of clusters. We propose that reductions in motoneuron size may promote early recruitment of EDL motoneurons, but that C‐bouton plasticity is not necessary to increase the force output required in response to muscle overload.
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Affiliation(s)
- Roger W P Kissane
- Institute of Ageing & Chronic Disease, University of Liverpool, Liverpool, UK.,School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Arash Ghaffari-Rafi
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Peter G Tickle
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | | | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Robert M Brownstone
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Calvin C Smith
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK
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Moriscot A, Miyabara EH, Langeani B, Belli A, Egginton S, Bowen TS. Firearms-related skeletal muscle trauma: pathophysiology and novel approaches for regeneration. NPJ Regen Med 2021; 6:17. [PMID: 33772028 PMCID: PMC7997931 DOI: 10.1038/s41536-021-00127-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 02/24/2021] [Indexed: 02/07/2023] Open
Abstract
One major cause of traumatic injury is firearm-related wounds (i.e., ballistic trauma), common in both civilian and military populations, which is increasing in prevalence and has serious long-term health and socioeconomic consequences worldwide. Common primary injuries of ballistic trauma include soft-tissue damage and loss, haemorrhage, bone fracture, and pain. The majority of injuries are of musculoskeletal origin and located in the extremities, such that skeletal muscle offers a major therapeutic target to aid recovery and return to normal daily activities. However, the underlying pathophysiology of skeletal muscle ballistic trauma remains poorly understood, with limited evidence-based treatment options. As such, this review will address the topic of firearm-related skeletal muscle injury and regeneration. We first introduce trauma ballistics and the immediate injury of skeletal muscle, followed by detailed coverage of the underlying biological mechanisms involved in regulating skeletal muscle dysfunction following injury, with a specific focus on the processes of muscle regeneration, muscle wasting and vascular impairments. Finally, we evaluate novel approaches for minimising muscle damage and enhancing muscle regeneration after ballistic trauma, which may have important relevance for primary care in victims of violence.
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Affiliation(s)
- Anselmo Moriscot
- grid.11899.380000 0004 1937 0722Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Elen H. Miyabara
- grid.11899.380000 0004 1937 0722Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | | | - Antonio Belli
- grid.6572.60000 0004 1936 7486NIHR Surgical Reconstruction and Microbiology Research Centre, University of Birmingham, Birmingham, UK
| | - Stuart Egginton
- grid.9909.90000 0004 1936 8403School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - T. Scott Bowen
- grid.9909.90000 0004 1936 8403School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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14
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Espino-Gonzalez E, Tickle PG, Benson AP, Kissane RWP, Askew GN, Egginton S, Bowen TS. Abnormal skeletal muscle blood flow, contractile mechanics and fibre morphology in a rat model of obese-HFpEF. J Physiol 2021; 599:981-1001. [PMID: 33347612 PMCID: PMC7898698 DOI: 10.1113/jp280899] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/04/2020] [Indexed: 12/18/2022] Open
Abstract
KEY POINTS Heart failure is characterised by limb and respiratory muscle impairments that limit functional capacity and quality of life. However, compared with heart failure with reduced ejection fraction (HFrEF), skeletal muscle alterations induced by heart failure with preserved ejection fraction (HFpEF) remain poorly explored. Here we report that obese-HFpEF induces multiple skeletal muscle alterations in the rat hindlimb, including impaired muscle mechanics related to shortening velocity, fibre atrophy, capillary loss, and an impaired blood flow response to contractions that implies a perfusive oxygen delivery limitation. We also demonstrate that obese-HFpEF is characterised by diaphragmatic alterations similar to those caused by denervation - atrophy in Type IIb/IIx (fast/glycolytic) fibres and hypertrophy in Type I (slow/oxidative) fibres. These findings extend current knowledge in HFpEF skeletal muscle physiology, potentially underlying exercise intolerance, which may facilitate future therapeutic approaches. ABSTRACT Peripheral skeletal muscle and vascular alterations induced by heart failure with preserved ejection fraction (HFpEF) remain poorly identified, with limited therapeutic targets. This study used a cardiometabolic obese-HFpEF rat model to comprehensively phenotype skeletal muscle mechanics, blood flow, microvasculature and fibre atrophy. Lean (n = 8) and obese-HFpEF (n = 8) ZSF1 rats were compared. Skeletal muscles (soleus and diaphragm) were assessed for in vitro contractility (isometric and isotonic properties) alongside indices of fibre-type cross-sectional area, myosin isoform, and capillarity, and estimated muscle PO2 . In situ extensor digitorum longus (EDL) contractility and femoral blood flow were assessed. HFpEF soleus demonstrated lower absolute maximal force by 22%, fibre atrophy by 24%, a fibre-type shift from I to IIa, and a 17% lower capillary-to-fibre ratio despite increased capillary density (all P < 0.05) with preserved muscle PO2 (P = 0.115) and isometric specific force (P > 0.05). Soleus isotonic properties (shortening velocity and power) were impaired by up to 17 and 22%, respectively (P < 0.05), while the magnitude of the exercise hyperaemia was attenuated by 73% (P = 0.012) in line with higher muscle fatigue by 26% (P = 0.079). Diaphragm alterations (P < 0.05) included Type IIx fibre atrophy despite Type I/IIa fibre hypertrophy, with increased indices of capillarity alongside preserved contractile properties during isometric, isotonic, and cyclical contractions. In conclusion, obese-HFpEF rats demonstrated blunted skeletal muscle blood flow during contractions in parallel to microvascular structural remodelling, fibre atrophy, and isotonic contractile dysfunction in the locomotor muscles. In contrast, diaphragm phenotype remained well preserved. This study identifies numerous muscle-specific impairments that could exacerbate exercise intolerance in obese-HFpEF.
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Affiliation(s)
- Ever Espino-Gonzalez
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Peter G Tickle
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Alan P Benson
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Roger W P Kissane
- Department of Musculoskeletal & Ageing Science, University of Liverpool, Liverpool, UK
| | - Graham N Askew
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - T Scott Bowen
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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15
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Kissane RWP, Tickle PG, Doody NE, Al-Shammari AA, Egginton S. Distinct structural and functional angiogenic responses are induced by different mechanical stimuli. Microcirculation 2021; 28:e12677. [PMID: 33417723 PMCID: PMC8614118 DOI: 10.1111/micc.12677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 12/23/2020] [Indexed: 11/29/2022]
Abstract
Objective Adequacy of the microcirculation is essential for maintaining repetitive skeletal muscle function while avoiding fatigue. It is unclear, however, whether capillary remodelling after different angiogenic stimuli is comparable in terms of vessel distribution and consequent functional adaptations. We determined the physiological consequences of two distinct mechanotransductive stimuli: (1) overload‐mediated abluminal stretch (OV); (2) vasodilator‐induced shear stress (prazosin, PR). Methods In situ EDL fatigue resistance was determined after 7 or 14 days of intervention, in addition to measurements of femoral artery flow. Microvascular composition (muscle histology) and oxidative capacity (citrate synthase activity) were quantified, and muscle PO2 calculated using advanced mathematical modelling. Results Compared to controls, capillary‐to‐fiber ratio was higher after OV14 (134%, p < .001) and PR14 (121%, p < .05), although fatigue resistance only improved after overload (7 days: 135%, 14 days: 125%, p < .05). In addition, muscle overload improved local capillary supply indices and reduced CS activity, while prazosin treatment failed to alter either index of aerobic capacity. Conclusion Targeted capillary growth in response to abluminal stretch is a potent driver of improved muscle fatigue resistance, while shear stress‐driven angiogenesis has no beneficial effect on muscle function. In terms of capillarity, more is not necessarily better.
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Affiliation(s)
- Roger W P Kissane
- Department of Musculoskeletal & Ageing Science, University of Liverpool, Liverpool, UK.,School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Peter G Tickle
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Natalie E Doody
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Abdullah A Al-Shammari
- Department of Mathematics, Faculty of Sciences, Kuwait University, Khaldiya, Kuwait.,Department of Genetics & Bioinformatics, Dasman Diabetes Institute, Dasman, Kuwait
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds, UK
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16
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Warren PM, Kissane RWP, Egginton S, Kwok JCF, Askew GN. Oxygen transport kinetics underpin rapid and robust diaphragm recovery following chronic spinal cord injury. J Physiol 2020; 599:1199-1224. [PMID: 33146892 PMCID: PMC7894160 DOI: 10.1113/jp280684] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 10/29/2020] [Indexed: 12/16/2022] Open
Abstract
Key points Spinal treatment can restore diaphragm function in all animals 1 month following C2 hemisection induced paralysis. Greater recovery occurs the longer after injury the treatment is applied. Through advanced assessment of muscle mechanics, innovative histology and oxygen tension modelling, we have comprehensively characterized in vivo diaphragm function and phenotype. Muscle work loops reveal a significant deficit in diaphragm functional properties following chronic injury and paralysis, which are normalized following restored muscle activity caused by plasticity‐induced spinal reconnection. Injury causes global and local alterations in diaphragm muscle vascular supply, limiting oxygen diffusion and disturbing function. Restoration of muscle activity reverses these alterations, restoring oxygen supply to the tissue and enabling recovery of muscle functional properties. There remain metabolic deficits following restoration of diaphragm activity, probably explaining only partial functional recovery. We hypothesize that these deficits need to be resolved to restore complete respiratory motor function.
Abstract Months after spinal cord injury (SCI), respiratory deficits remain the primary cause of morbidity and mortality for patients. It is possible to induce partial respiratory motor functional recovery in chronic SCI following 2 weeks of spinal neuroplasticity. However, the peripheral mechanisms underpinning this recovery are largely unknown, limiting development of new clinical treatments with potential for complete functional restoration. Utilizing a rat hemisection model, diaphragm function and paralysis was assessed and recovered at chronic time points following trauma through chondroitinase ABC induced neuroplasticity. We simulated the diaphragm's in vivo cyclical length change and activity patterns using the work loop technique at the same time as assessing global and local measures of the muscles histology to quantify changes in muscle phenotype, microvascular composition, and oxidative capacity following injury and recovery. These data were fed into a physiologically informed model of tissue oxygen transport. We demonstrate that hemidiaphragm paralysis causes muscle fibre hypertrophy, maintaining global oxygen supply, although it alters isolated muscle kinetics, limiting respiratory function. Treatment induced recovery of respiratory activity normalized these effects, increasing oxygen supply, restoring optimal diaphragm functional properties. However, metabolic demands of the diaphragm were significantly reduced following both injury and recovery, potentially limiting restoration of normal muscle performance. The mechanism of rapid respiratory muscle recovery following spinal trauma occurs through oxygen transport, metabolic demand and functional dynamics of striated muscle. Overall, these data support a systems‐wide approach to the treatment of SCI, and identify new targets to mediate complete respiratory recovery. Spinal treatment can restore diaphragm function in all animals 1 month following C2 hemisection induced paralysis. Greater recovery occurs the longer after injury the treatment is applied. Through advanced assessment of muscle mechanics, innovative histology and oxygen tension modelling, we have comprehensively characterized in vivo diaphragm function and phenotype. Muscle work loops reveal a significant deficit in diaphragm functional properties following chronic injury and paralysis, which are normalized following restored muscle activity caused by plasticity‐induced spinal reconnection. Injury causes global and local alterations in diaphragm muscle vascular supply, limiting oxygen diffusion and disturbing function. Restoration of muscle activity reverses these alterations, restoring oxygen supply to the tissue and enabling recovery of muscle functional properties. There remain metabolic deficits following restoration of diaphragm activity, probably explaining only partial functional recovery. We hypothesize that these deficits need to be resolved to restore complete respiratory motor function.
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Affiliation(s)
- Philippa M Warren
- The Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London, UK.,School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Roger W P Kissane
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.,Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Jessica C F Kwok
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.,Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic
| | - Graham N Askew
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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17
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Bowen TS, Egginton S. Environmental stress influences mitochondrial metabolism in vascular cells: consequences for angiogenesis. Vasc Biol 2020; 1:H111-H116. [PMID: 32923962 PMCID: PMC7439850 DOI: 10.1530/vb-19-0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 10/01/2019] [Indexed: 11/08/2022]
Abstract
While the important and varied roles that vascular cells play in both health and disease is well recognised, the focus on potential therapeutic targets continually shifts as new players emerge. Here, we outline how mitochondria may be viewed as more than simply energy-generating organelles, but instead as important sentinels of metabolic health and effectors of appropriate responses to physiological challenges.
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Affiliation(s)
- T Scott Bowen
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds, UK
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18
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Garnham JO, Roberts LD, Espino-Gonzalez E, Whitehead A, Swoboda PP, Koshy A, Gierula J, Paton MF, Cubbon RM, Kearney MT, Egginton S, Bowen TS, Witte KK. Chronic heart failure with diabetes mellitus is characterized by a severe skeletal muscle pathology. J Cachexia Sarcopenia Muscle 2020; 11:394-404. [PMID: 31863644 PMCID: PMC7113493 DOI: 10.1002/jcsm.12515] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 10/07/2019] [Accepted: 10/17/2019] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Patients with coexistent chronic heart failure (CHF) and diabetes mellitus (DM) demonstrate greater exercise limitation and worse prognosis compared with CHF patients without DM, even when corrected for cardiac dysfunction. Understanding the origins of symptoms in this subgroup may facilitate development of targeted treatments. We therefore characterized the skeletal muscle phenotype and its relationship to exercise limitation in patients with diabetic heart failure (D-HF). METHODS In one of the largest muscle sampling studies in a CHF population, pectoralis major biopsies were taken from age-matched controls (n = 25), DM (n = 10), CHF (n = 52), and D-HF (n = 28) patients. In situ mitochondrial function and reactive oxygen species, fibre morphology, capillarity, and gene expression analyses were performed and correlated to whole-body exercise capacity. RESULTS Mitochondrial respiration, content, coupling efficiency, and intrinsic function were lower in D-HF patients compared with other groups (P < 0.05). A unique mitochondrial complex I dysfunction was present in D-HF patients only (P < 0.05), which strongly correlated to exercise capacity (R2 = 0.64; P < 0.001). Mitochondrial impairments in D-HF corresponded to higher levels of mitochondrial reactive oxygen species (P < 0.05) and lower gene expression of anti-oxidative enzyme superoxide dismutase 2 (P < 0.05) and complex I subunit NDUFS1 (P < 0.05). D-HF was also associated with severe fibre atrophy (P < 0.05) and reduced local fibre capillarity (P < 0.05). CONCLUSIONS Patients with D-HF develop a specific skeletal muscle pathology, characterized by mitochondrial impairments, fibre atrophy, and derangements in the capillary network that are linked to exercise intolerance. These novel preliminary data support skeletal muscle as a potential therapeutic target for treating patients with D-HF.
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Affiliation(s)
- Jack O Garnham
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Lee D Roberts
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Ever Espino-Gonzalez
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Anna Whitehead
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Peter P Swoboda
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Aaron Koshy
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - John Gierula
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Maria F Paton
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Richard M Cubbon
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Mark T Kearney
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - T Scott Bowen
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Klaus K Witte
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
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19
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Tickle PG, Hendrickse PW, Degens H, Egginton S. Impaired skeletal muscle performance as a consequence of random functional capillary rarefaction can be restored with overload-dependent angiogenesis. J Physiol 2020; 598:1187-1203. [PMID: 32012275 PMCID: PMC7154729 DOI: 10.1113/jp278975] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 01/20/2020] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS Loss of skeletal muscle capillaries is thought to contribute to a reduction in exercise tolerance, but the relative contribution of a compromised microcirculation with disease, in isolation of co-morbidities, to impaired muscle function is unknown. We therefore developed a novel method to randomly occlude capillaries in the rat hindlimb to mimic the capillary rarefaction observed in many conditions. We demonstrate that muscle fatigue resistance is closely coupled with functional microvascular density, independent of arterial blood flow, while disturbance of the microcirculation leads to long-term impairment of muscle function if left untreated. Mechanical stretch due to muscle overload causes a restoration of fatigue resistance via angiogenic remodelling. These observations highlight the importance of a healthy microcirculation and suggest that restoring impaired microvascular supply, regardless of disease co-morbidities, will assist recovery of exercise tolerance in a variety of conditions that limit quality of life. ABSTRACT To what extent microvascular rarefaction contributes to impaired skeletal muscle function remains unknown. Our understanding of whether pathological changes in the microcirculation can be reversed remains limited by a lack of basic physiological data in otherwise healthy tissue. The principal objectives here were to: (1) quantify the effect of random microvascular rarefaction on limb perfusion and muscle performance, and (2) determine if these changes could be reversed. We developed a novel protocol in rats whereby microspheres injected into the femoral artery allowed a unilateral reduction in functional capillary density in the extensor digitorum longus (EDL), and assessed acute and chronic effects on muscle function. Simultaneous bilateral EDL force and hindlimb blood flow measurements were made during electrical stimulation. Following functional capillary rarefaction there was an acute microsphere dose-dependent reduction in muscle fatigue resistance (P < 0.001), despite preserved femoral artery perfusion. Histological analysis of EDL samples taken from injected animals confirmed a positive correlation between the proportion of functional capillaries and fatigue resistance (P = 0.002). Such impaired performance persisted for at least 2 weeks (P = 0.016). Concomitant mechanical overload improved both perfused capillary density and fatigue resistance (P<0.05), confirming that the capacity for muscle remodelling was retained following chronic distributed ischaemia, and that the impact of capillary rarefaction could be alleviated. These results demonstrate that loss of functional capillaries is detrimental to muscle function, even in otherwise healthy tissue, independent of arterial perfusion. Restoration of muscle performance following a mechanical overload stimulus indicates that angiogenic treatments to alleviate microvascular rarefaction may be key to restoring exercise tolerance.
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Affiliation(s)
| | - Paul W Hendrickse
- Department of Life Sciences, Manchester Metropolitan University, UK.,Institute of Sport Science and Innovations, Lithuanian Sports University, Lithuania
| | - Hans Degens
- Department of Life Sciences, Manchester Metropolitan University, UK.,Institute of Sport Science and Innovations, Lithuanian Sports University, Lithuania
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20
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Baum O, Bernd J, Becker S, Odriozola A, Zuber B, Tschanz SA, Zakrzewicz A, Egginton S, Berkholz J. Structural Microangiopathies in Skeletal Muscle Related to Systemic Vascular Pathologies in Humans. Front Physiol 2020; 11:28. [PMID: 32116748 PMCID: PMC7013089 DOI: 10.3389/fphys.2020.00028] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 01/15/2020] [Indexed: 12/17/2022] Open
Abstract
It is unclear how microangiopathic changes in skeletal muscle vary among systemic vascular pathologies. We therefore analyzed the capillary fine structure in skeletal muscle from patients with arterial hypertension (HYPT), diabetes mellitus type 2 (T2DM) or intermittent claudication – peripheral arterial disease (IC/PAD). Tablet-based image analysis (TBIA) was carried out to largely re-evaluate 5,000 transmission electron micrographs of capillaries from 126 vastus lateralis biopsies of 75 individuals (HYPT, T2DM or IC/PAD patients as well as healthy individuals before and after endurance exercise training) used in previous morphometric studies, but assessed using stereological counting grids of different sizes. Serial block-face scanning electron microscopy (SBFSEM) of mouse skeletal muscle was used for validation of the particular fine structural events observed in human biopsies. The peri-capillary basement membrane (BM) was 38.5 and 45.5% thicker (P < 0.05) in T2DM and IC/PAD patients than in the other groups. A 17.7–39.6% lower (P < 0.05) index for intraluminal endothelial cell (EC) surface enlargement by projections was exclusively found in T2DM patients by TBIA morphometry. The proportion of capillaries with disrupted BM between pericytes (PC) and EC was higher (P < 0.05) in HYPT (33.2%) and T2DM (38.7%) patients than in the control group. Empty EC-sockets were more frequent (P < 0.05) in the three patient groups (20.6% in HYPT, 27.1% in T2DM, 30.0% in IC/PAD) than in the healthy individuals. SBFSEM confirmed that EC-sockets may exhibit close proximity to the capillary lumen. Our comparative morphometric analysis demonstrated that structural arrangement of skeletal muscle capillaries is more affected in T2DM than in HYPT or IC/PAD, although some similar elements of remodeling were found. The increased frequency of empty EC-sockets in the three patient groups indicates that the PC-EC interaction is commonly disturbed in these systemic vascular pathologies.
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Affiliation(s)
- Oliver Baum
- Institut für Physiologie, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jonathan Bernd
- Institut für Physiologie, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Samuel Becker
- Institut für Physiologie, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | | | - Benoît Zuber
- Institute of Anatomy, University of Bern, Bern, Switzerland
| | | | - Andreas Zakrzewicz
- Institut für Physiologie, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Janine Berkholz
- Institut für Physiologie, Charité - Universitätsmedizin Berlin, Berlin, Germany
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21
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Affiliation(s)
- Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, Leeds, United Kingdom
| | - Roger W P Kissane
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, Leeds, United Kingdom
| | - Abdullah A Al-Shammari
- Department of Mathematics, Faculty of Sciences, Kuwait University, Khaldiya, Kuwait.,Department of Genetics and Bioinformatics, Dasman Diabetes Institute, Dasman, Kuwait
| | - Eamonn A Gaffney
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom
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22
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23
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Fowler ED, Hauton D, Boyle J, Egginton S, Steele DS, White E. Energy Metabolism in the Failing Right Ventricle: Limitations of Oxygen Delivery and the Creatine Kinase System. Int J Mol Sci 2019; 20:E1805. [PMID: 31013688 PMCID: PMC6514649 DOI: 10.3390/ijms20081805] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 04/08/2019] [Accepted: 04/10/2019] [Indexed: 12/15/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) results in hypertrophic remodeling of the right ventricle (RV) to overcome increased pulmonary pressure. This increases the O2 consumption of the myocardium, and without a concomitant increase in energy generation, a mismatch with demand may occur. Eventually, RV function can no longer be sustained, and RV failure occurs. Beta-adrenergic blockers (BB) are thought to improve survival in left heart failure, in part by reducing energy expenditure and hypertrophy, however they are not currently a therapy for PAH. The monocrotaline (MCT) rat model of PAH was used to investigate the consequence of RV failure on myocardial oxygenation and mitochondrial function. A second group of MCT rats was treated daily with the beta-1 blocker metoprolol (MCT + BB). Histology confirmed reduced capillary density and increased capillary supply area without indications of capillary rarefaction in MCT rats. A computer model of O2 flux was applied to the experimentally recorded capillary locations and predicted a reduction in mean tissue PO2 in MCT rats. The fraction of hypoxic tissue (defined as PO2 < 0.5 mmHg) was reduced following beta-1 blocker (BB) treatment. The functionality of the creatine kinase (CK) energy shuttle was measured in permeabilized RV myocytes by sequential ADP titrations in the presence and absence of creatine. Creatine significantly decreased the KmADP in cells from saline-injected control (CON) rats, but not MCT rats. The difference in KmADP with or without creatine was not different in MCT + BB cells compared to CON or MCT cells. Improved myocardial energetics could contribute to improved survival of PAH with chronic BB treatment.
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Affiliation(s)
- Ewan D Fowler
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds LS2 9JT, UK.
- Cardiac Research Laboratories, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK.
| | - David Hauton
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds LS2 9JT, UK.
- Metabolomics Research Group, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, UK.
| | - John Boyle
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds LS2 9JT, UK.
| | - Stuart Egginton
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds LS2 9JT, UK.
| | - Derek S Steele
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds LS2 9JT, UK.
| | - Ed White
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds LS2 9JT, UK.
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Joyce W, Egginton S, Farrell AP, Axelsson M. Adrenergic and adenosinergic regulation of the cardiovascular system in an Antarctic icefish: Insight into central and peripheral determinants of cardiac output. Comp Biochem Physiol A Mol Integr Physiol 2019; 230:28-38. [DOI: 10.1016/j.cbpa.2018.12.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/19/2018] [Accepted: 12/19/2018] [Indexed: 01/27/2023]
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Al-Shammari AA, Kissane RWP, Holbek S, Mackey AL, Andersen TR, Gaffney EA, Kjaer M, Egginton S. Integrated method for quantitative morphometry and oxygen transport modeling in striated muscle. J Appl Physiol (1985) 2019; 126:544-557. [DOI: 10.1152/japplphysiol.00170.2018] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Identifying structural limitations in O2 transport is primarily restricted by current methods employed to characterize the nature of physiological remodeling. Inadequate resolution or breadth of available data has impaired development of routine diagnostic protocols and effective therapeutic strategies. Understanding O2 transport within striated muscle faces major challenges, most notably in quantifying how well individual fibers are supplied by the microcirculation, which has necessitated exploring tissue O2 supply using theoretical modeling of diffusive exchange. With capillary domains identified as a suitable model for the description of local O2 supply and requiring less computation than numerically calculating the trapping regions that are supplied by each capillary via biophysical transport models, we sought to design a high-throughput method for histological analysis. We present an integrated package that identifies optimal protocols for identification of important input elements, processing of digitized images with semiautomated routines, and incorporation of these data into a mathematical modeling framework with computed output visualized as the tissue partial pressure of O2 (Po2) distribution across a biopsy sample. Worked examples are provided using muscle samples from experiments involving rats and humans. NEW & NOTEWORTHY Progress in quantitative morphometry and analytical modeling has tended to develop independently. Real diagnostic power lies in harnessing both disciplines within one user-friendly package. We present a semiautomated, high-throughput tool for determining muscle phenotype from biopsy material, which also provides anatomically relevant input to quantify tissue oxygenation, in a coherent package not previously available to nonspecialist investigators.
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Affiliation(s)
- Abdullah A. Al-Shammari
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom
- Department of Mathematics, Faculty of Science, Kuwait University, Khaldiya, Kuwait
| | - Roger W. P. Kissane
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | | | - Abigail L. Mackey
- Institute of Sports Medicine, Copenhagen, Department of Orthopaedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark
- Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas R. Andersen
- Copenhagen Centre for Team Sport and Health, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Eamonn A. Gaffney
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom
| | - Michael Kjaer
- Institute of Sports Medicine, Copenhagen, Department of Orthopaedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark
- Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
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Egginton S, Axelsson M, Crockett EL, O’Brien KM, Farrell AP. Maximum cardiac performance of Antarctic fishes that lack haemoglobin and myoglobin: exploring the effect of warming on nature's natural knockouts. Conserv Physiol 2019; 7:coz049. [PMID: 31620287 PMCID: PMC6788497 DOI: 10.1093/conphys/coz049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 06/18/2019] [Accepted: 06/27/2019] [Indexed: 05/04/2023]
Abstract
Antarctic notothenioids, some of which lack myoglobin (Mb) and/or haemoglobin (Hb), are considered extremely stenothermal, which raises conservation concerns since Polar regions are warming at unprecedented rates. Without reliable estimates of maximum cardiac output ([Formula: see text]), it is impossible to assess their physiological scope in response to warming seas. Therefore, we compared cardiac performance of two icefish species, Chionodraco rastrospinosus (Hb-Mb+) and Chaenocephalus aceratus (Hb-Mb-), with a related notothenioid, Notothenia coriiceps (Hb+Mb+) using an in situ perfused heart preparation. The maximum [Formula: see text], heart rate (f H), maximum cardiac work (W C) and relative ventricular mass of N. coriiceps at 1°C were comparable to temperate-water teleosts, and acute warming to 4°C increased f H and W C, as expected. In contrast, icefish hearts accommodated a higher maximum stroke volume (V S) and maximum [Formula: see text] at 1°C, but their unusually large hearts had a lower f H and maximum afterload tolerance than N. coriiceps at 1°C. Furthermore, maximum V S, maximum [Formula: see text] and f H were all significantly higher for the Hb-Mb+ condition compared with the Hb-Mb- condition, a potential selective advantage when coping with environmental warming. Like N. coriiceps, both icefish species increased f H at 4°C. Acutely warming C. aceratus increased maximum [Formula: see text], while C. rastrospinosus (like N. coriiceps) held at 4°C for 1 week maintained maximum [Formula: see text] when tested at 4°C. These experiments involving short-term warming should be followed up with long-term acclimation studies, since the maximum cardiac performance of these three Antarctic species studied seem to be tolerant of temperatures in excess of predictions associated with global warming.
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Affiliation(s)
- Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg SE-405 30, Sweden
| | | | - Kristin M O’Brien
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK AK99775, USA
| | - Anthony P Farrell
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 124, Canada
- Corresponding author: Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
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Harter TS, Sackville MA, Wilson JM, Metzger DCH, Egginton S, Esbaugh AJ, Farrell AP, Brauner CJ. A solution to Nature's haemoglobin knockout: a plasma-accessible carbonic anhydrase catalyses CO 2 excretion in Antarctic icefish gills. ACTA ACUST UNITED AC 2018; 221:jeb.190918. [PMID: 30291156 DOI: 10.1242/jeb.190918] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 09/27/2018] [Indexed: 01/29/2023]
Abstract
In all vertebrates studied to date, CO2 excretion depends on the enzyme carbonic anhydrase (CA) that catalyses the rapid conversion of HCO3 - to CO2 at the gas-exchange organs. The largest pool of CA is present within red blood cells (RBCs) and, in some vertebrates, plasma-accessible CA (paCA) isoforms participate in CO2 excretion. However, teleost fishes typically do not have paCA at the gills and CO2 excretion is reliant entirely on RBC CA - a strategy that is not possible in icefishes. As the result of a natural knockout, Antarctic icefishes (Channichthyidae) are the only known vertebrates that do not express haemoglobin (Hb) as adults, and largely lack RBCs in the circulation (haematocrit <1%). Previous work has indicated the presence of high levels of membrane-bound CA activity in the gills of icefishes, but without determining its cellular orientation. Thus, we hypothesised that icefishes express a membrane-bound CA isoform at the gill that is accessible to the blood plasma. The CA distribution was compared in the gills of two closely related notothenioid species, one with Hb and RBCs (Notothenia rossii) and one without (Champsocephalus gunnari). Molecular, biochemical and immunohistochemical markers indicate high levels of a Ca4 isoform in the gills of the icefish (but not the red-blooded N. rossii), in a plasma-accessible location that is consistent with a role in CO2 excretion. Thus, in the absence of RBC CA, the icefish gill could exclusively provide the catalytic activity necessary for CO2 excretion - a pathway that is unlike that of any other vertebrate.
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Affiliation(s)
- Till S Harter
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Michael A Sackville
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Jonathan M Wilson
- Department of Biology, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada
| | - David C H Metzger
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Stuart Egginton
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Andrew J Esbaugh
- Marine Science Institute, University of Texas at Austin, Port Aransas, TX 78373, USA
| | - Anthony P Farrell
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.,Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Colin J Brauner
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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28
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Joyce W, Egginton S, Farrell AP, Crockett EL, O'Brien KM, Axelsson M. Exploring nature's natural knockouts: in vivo cardiorespiratory performance of Antarctic fishes during acute warming. ACTA ACUST UNITED AC 2018; 221:jeb.183160. [PMID: 29967219 DOI: 10.1242/jeb.183160] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/25/2018] [Indexed: 01/09/2023]
Abstract
We tested the hypothesis that blackfin icefish (Chaenocephalus aceratus), one of the six species in the family Channichthyidae (the icefishes) that do not express haemoglobin and myoglobin, lack regulatory cardiovascular flexibility during acute warming and activity. The experimental protocols were designed to optimize the surgical protocol and minimize stress. First, minimally invasive heart rate (fH) measurements were made during a thermal ramp until cardiac failure in C. aceratus and compared with those from the closely related red-blooded black rockcod (Notothenia coriiceps). Then, integrative cardiovascular adjustments were more extensively studied using flow probes and intravascular catheters in C. aceratus during acute warming (from 0 to 8°C) at rest and after imposed activity. Chaenocephalus aceratus had a lower routine fH than N. coriiceps (9 beats min-1 versus 14 beats min-1) and a lower peak fH during acute warming (38 beats min-1 versus 55 beats min-1) with a similar cardiac breakpoint temperature (13 and 14°C, respectively). Routine cardiac output (Q̇) for C. aceratus at ∼0°C was much lower (26.6 ml min-1 kg-1) than previously reported, probably because fish in the present study had a low fH (12 beats min-1) indicative of a high routine vagal tone and low stress. Chaenocephalus aceratus increased oxygen consumption during acute warming and with activity. Correspondingly, Q̇ increased considerably (maximally 86.3 ml min-1 kg-1), as did vascular conductance (5-fold). Thus, unlike earlier suggestions, these data provide convincing evidence that icefish can mount a well-developed cardiovascular regulation of heart rate, cardiac output and vascular conductance, and this regulatory capacity provides flexibility during acute warming.
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Affiliation(s)
- William Joyce
- Department of Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Anthony P Farrell
- Department of Zoology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC 45, Canada
| | | | - Kristin M O'Brien
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, 4139 90 Gothenburg, Sweden
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29
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O'Brien KM, Rix AS, Egginton S, Farrell AP, Crockett EL, Schlauch K, Woolsey R, Hoffman M, Merriman S. Cardiac mitochondrial metabolism may contribute to differences in thermal tolerance of red- and white-blooded Antarctic notothenioid fishes. J Exp Biol 2018; 221:jeb177816. [PMID: 29895681 PMCID: PMC6104818 DOI: 10.1242/jeb.177816] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 06/04/2018] [Indexed: 12/18/2022]
Abstract
Studies in temperate fishes provide evidence that cardiac mitochondrial function and the capacity to fuel cardiac work contribute to thermal tolerance. Here, we tested the hypothesis that decreased cardiac aerobic metabolic capacity contributes to the lower thermal tolerance of the haemoglobinless Antarctic icefish, Chaenocephalus aceratus, compared with that of the red-blooded Antarctic species, Notothenia coriiceps. Maximal activities of citrate synthase (CS) and lactate dehydrogenase (LDH), respiration rates of isolated mitochondria, adenylate levels and changes in mitochondrial protein expression were quantified from hearts of animals held at ambient temperature or exposed to their critical thermal maximum (CTmax). Compared with C. aceratus, activity of CS, ATP concentration and energy charge were higher in hearts of N. coriiceps at ambient temperature and CTmax While state 3 mitochondrial respiration rates were not impaired by exposure to CTmax in either species, state 4 rates, indicative of proton leakage, increased following exposure to CTmax in C. aceratus but not N. coriiceps The interactive effect of temperature and species resulted in an increase in antioxidants and aerobic metabolic enzymes in N. coriiceps but not in C. aceratus Together, our results support the hypothesis that the lower aerobic metabolic capacity of C. aceratus hearts contributes to its low thermal tolerance.
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Affiliation(s)
- Kristin M O'Brien
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Anna S Rix
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Anthony P Farrell
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | | | - Karen Schlauch
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA
| | - Rebekah Woolsey
- Nevada Proteomics Center, University of Nevada, Reno, NV 89557, USA
| | - Megan Hoffman
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Sean Merriman
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
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30
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Joyce W, Axelsson M, Egginton S, Farrell AP, Crockett EL, O’Brien KM. The effects of thermal acclimation on cardio-respiratory performance in an Antarctic fish ( Notothenia coriiceps). Conserv Physiol 2018; 6:coy069. [PMID: 30568798 PMCID: PMC6291619 DOI: 10.1093/conphys/coy069] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/13/2018] [Accepted: 11/26/2018] [Indexed: 05/21/2023]
Abstract
The Southern Ocean has experienced stable, cold temperatures for over 10 million years, yet particular regions are currently undergoing rapid warming. To investigate the impacts of warming on cardiovascular oxygen transport, we compared the cardio-respiratory performance in an Antarctic notothenioid (Notothenia coriiceps) that was maintained at 0 or 5°C for 6.0-9.5 weeks. When compared at the fish's respective acclimation temperature, the oxygen consumption rate and cardiac output were significantly higher in 5°C-acclimated than 0°C-acclimated fish. The 2.7-fold elevation in cardiac output in 5°C-acclimated fish (17.4 vs. 6.5 ml min-1 kg-1) was predominantly due to a doubling of stroke volume, likely in response to increased cardiac preload, as measured by higher central venous pressure (0.15 vs. 0.08 kPa); tachycardia was minor (29.5 vs. 25.2 beats min-1). When fish were acutely warmed, oxygen consumption rate increased by similar amounts in 0°C- and 5°C-acclimated fish at equivalent test temperatures. In both acclimation groups, the increases in oxygen consumption rate during acute heating were supported by increased cardiac output achieved by elevating heart rate, while stroke volume changed relatively little. Cardiac output was similar between both acclimation groups until 12°C when cardiac output became significantly higher in 5°C-acclimated fish, driven largely by their higher stroke volume. Although cardiac arrhythmias developed at a similar temperature (~14.5°C) in both acclimation groups, the hearts of 5°C-acclimated fish continued to pump until significantly higher temperatures (CTmax for cardiac function 17.7 vs. 15.0°C for 0°C-acclimated fish). These results demonstrate that N. coriiceps is capable of increasing routine cardiac output during both acute and chronic warming, although the mechanisms are different (heart rate-dependent versus primarily stroke volume-dependent regulation, respectively). Cardiac performance was enhanced at higher temperatures following 5°C acclimation, suggesting cardiovascular function may not constrain the capacity of N. coriiceps to withstand a warming climate.
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Affiliation(s)
- William Joyce
- Department of Zoophysiology, Aarhus University, Aarhus C, Denmark
- Corresponding author: Department of Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark.
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Anthony P Farrell
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | | | - Kristin M O’Brien
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
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Kissane RWP, Egginton S, Askew GN. Regional variation in the mechanical properties and fibre-type composition of the rat extensor digitorum longus muscle. Exp Physiol 2017; 103:111-124. [DOI: 10.1113/ep086483] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 10/23/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Roger W. P. Kissane
- School of Biomedical Sciences; Faculty of Biological Sciences, University of Leeds; Leeds UK
| | - Stuart Egginton
- School of Biomedical Sciences; Faculty of Biological Sciences, University of Leeds; Leeds UK
| | - Graham N. Askew
- School of Biomedical Sciences; Faculty of Biological Sciences, University of Leeds; Leeds UK
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Fujisawa T, Wang K, Niu XL, Egginton S, Ahmad S, Hewett P, Kontos CD, Ahmed A. Angiopoietin-1 promotes atherosclerosis by increasing the proportion of circulating Gr1+ monocytes. Cardiovasc Res 2017; 113:81-89. [PMID: 28069704 PMCID: PMC5220674 DOI: 10.1093/cvr/cvw223] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 10/11/2016] [Accepted: 10/17/2016] [Indexed: 01/22/2023] Open
Abstract
Aims Atherosclerosis is a chronic inflammatory disease occurring within the artery wall. A crucial step in atherogenesis is the infiltration and retention of monocytes into the subendothelial space of large arteries induced by chemokines and growth factors. Angiopoietin-1 (Ang-1) regulates angiogenesis and reduces vascular permeability and has also been reported to promote monocyte migration in vitro. We investigated the role of Ang-1 in atherosclerosis-prone apolipoprotein-E (Apo-E) knockout mouse. Methods and results Apo-E knockout (Apo-E-/-) mice fed a western or normal chow diet received a single iv injection of adenovirus encoding Ang-1 or control vector. Adenovirus-mediated systemic expression of Ang-1 induced a significant increase in early atherosclerotic lesion size and monocyte/macrophage accumulation compared with control animals receiving empty vector. Ang-1 significantly increased plasma MCP-1 and VEGF levels as measured by ELISA. FACS analysis showed that Ang-1 selectively increased inflammatory Gr1+ monocytes in the circulation, while the cell-surface expression of CD11b, which mediates monocyte emigration, was significantly reduced. Conclusions Ang-1 specifically increases circulating Gr1+ inflammatory monocytes and increases monocyte/macrophage retention in atherosclerotic plaques, thereby contributing to development of atherosclerosis.
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Affiliation(s)
- Takeshi Fujisawa
- Aston Medical Research Institute, Aston Medical School, Aston University, Birmingham B4 7ET, U.K.,Gustav Born Centre for Vascular Biology and BHF Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Keqing Wang
- Aston Medical Research Institute, Aston Medical School, Aston University, Birmingham B4 7ET, U.K; .,Gustav Born Centre for Vascular Biology and BHF Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Xi-Lin Niu
- Department of Medicine, Division of Cardiology, Duke University Medical Centre, Durham, NC 27710, USA
| | - Stuart Egginton
- Multidisciplinary Cardiovascular Research Centre, School of Biological Sciences, University of Leeds, Leeds, UK
| | - Shakil Ahmad
- Aston Medical Research Institute, Aston Medical School, Aston University, Birmingham B4 7ET, U.K.,Gustav Born Centre for Vascular Biology and BHF Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Peter Hewett
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Christopher D Kontos
- Department of Medicine, Division of Cardiology, Duke University Medical Centre, Durham, NC 27710, USA
| | - Asif Ahmed
- Aston Medical Research Institute, Aston Medical School, Aston University, Birmingham B4 7ET, U.K; .,Gustav Born Centre for Vascular Biology and BHF Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh EH16 4TJ, UK
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Rogers NJ, Jeffery HC, Claire S, Lewis DJ, Zikeli G, Hodges NJ, Egginton S, Nash GB, Pikramenou Z. Tailoring iridium luminescence and gold nanoparticle size for imaging of microvascular blood flow. Nanomedicine (Lond) 2017; 12:2725-2740. [PMID: 28960141 DOI: 10.2217/nnm-2017-0211] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
AIM Imaging of blood flow in narrow channels and close to vessel walls is important in cardiovascular research for understanding pathogenesis. Our aim was to provide novel nanoprobes with visible emission and long lifetimes as trackers of flow. MATERIALS & METHODS Gold nanoparticles coated with an iridium complex were prepared. Luminescence imaging was used to monitor their flows in different hematocrit blood and in murine tissues. RESULTS The velocities are independent of hematocrit level and the nanoparticles entering blood circulation can be clearly detected in vessels in lungs, mesentery and the skeletal muscle. CONCLUSION The work introduces for the first time iridium-based yellow-green luminescence with nanoparticle size of 100 nm for visualizing and monitoring flows with much higher resolution than conventional alternatives.
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Affiliation(s)
- Nicola J Rogers
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Hannah C Jeffery
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Sunil Claire
- Physical Sciences of Imaging in the Biological Sciences Doctoral Training Centre, University of Birmingham, Edgbaston, B15 2TT, UK
| | - David J Lewis
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Gerald Zikeli
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Nikolas J Hodges
- Physical Sciences of Imaging in the Biological Sciences Doctoral Training Centre, University of Birmingham, Edgbaston, B15 2TT, UK.,School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Stuart Egginton
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, B15 2TT, UK.,School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Gerard B Nash
- Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, B15 2TT, UK.,Physical Sciences of Imaging in the Biological Sciences Doctoral Training Centre, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Zoe Pikramenou
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK.,Physical Sciences of Imaging in the Biological Sciences Doctoral Training Centre, University of Birmingham, Edgbaston, B15 2TT, UK
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34
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Mortensen SP, Egginton S, Madsen M, Hansen JB, Munch GDW, Iepsen UW, Åkerström T, Pedersen BK, Hellsten Y. Alpha adrenergic receptor blockade increases capillarization and fractional O 2 extraction and lowers blood flow in contracting human skeletal muscle. Acta Physiol (Oxf) 2017; 221:32-43. [PMID: 28199786 DOI: 10.1111/apha.12857] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/17/2017] [Accepted: 02/10/2017] [Indexed: 12/28/2022]
Abstract
AIM To assess the effect of elevated basal shear stress on angiogenesis in humans and the role of enhanced skeletal muscle capillarization on blood flow and O2 extraction. METHODS Limb haemodynamics and O2 extraction were measured at rest and during one-leg knee-extensor exercise (12 and 24 W) in 10 healthy untrained young men before and after 4-week treatment with an α1 receptor-antagonist (Terazosin, 1-2 mg day-1 ). Corresponding biopsies were taken from the m. vastus lateralis. RESULTS Resting leg blood flow was increased by 57% 6 h following Terazosin treatment (P < 0.05), while basal capillary-to-fibre ratio was 1.69 ± 0.08 and increased to 1.90 ± 0.08 after treatment (P < 0.05). Leg O2 extraction during knee-extensor exercise was higher (4-5%; P < 0.05), leg blood flow and venous lactate levels lower (6-7%; P < 0.05), while leg VO2 was not different after Terazosin treatment. CONCLUSIONS These results demonstrate that daily treatment with an α-adrenergic receptor blocker induces capillary growth in human skeletal muscle, likely due to increased shear stress. The increase in capillarization resulted in an increased fractional O2 extraction, a lower blood flow and venous lactate levels in the exercising leg. The increase in capillarization, and concomitant functional readouts in the exercising leg, may provide a basis for novel angiotherapy.
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Affiliation(s)
- S. P. Mortensen
- The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research; Rigshospitalet; University of Copenhagen; Copenhagen Denmark
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense Denmark
| | - S. Egginton
- School of Biomedical Sciences; University of Leeds; Leeds UK
| | - M. Madsen
- Department of Nutrition, Exercise and Sport; University of Copenhagen; Copenhagen Denmark
| | - J. B. Hansen
- Department of Nutrition, Exercise and Sport; University of Copenhagen; Copenhagen Denmark
| | - G. D. W. Munch
- The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research; Rigshospitalet; University of Copenhagen; Copenhagen Denmark
| | - U. W. Iepsen
- The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research; Rigshospitalet; University of Copenhagen; Copenhagen Denmark
| | - T. Åkerström
- Department of Nutrition, Exercise and Sport; University of Copenhagen; Copenhagen Denmark
| | - B. K. Pedersen
- The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research; Rigshospitalet; University of Copenhagen; Copenhagen Denmark
| | - Y. Hellsten
- Department of Nutrition, Exercise and Sport; University of Copenhagen; Copenhagen Denmark
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Crowcombe J, Dhillon SS, Hurst RM, Egginton S, Müller F, Sík A, Tarte E. 3D Finite Element Electrical Model of Larval Zebrafish ECG Signals. PLoS One 2016; 11:e0165655. [PMID: 27824910 PMCID: PMC5100939 DOI: 10.1371/journal.pone.0165655] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 10/14/2016] [Indexed: 01/08/2023] Open
Abstract
Assessment of heart function in zebrafish larvae using electrocardiography (ECG) is a potentially useful tool in developing cardiac treatments and the assessment of drug therapies. In order to better understand how a measured ECG waveform is related to the structure of the heart, its position within the larva and the position of the electrodes, a 3D model of a 3 days post fertilisation (dpf) larval zebrafish was developed to simulate cardiac electrical activity and investigate the voltage distribution throughout the body. The geometry consisted of two main components; the zebrafish body was modelled as a homogeneous volume, while the heart was split into five distinct regions (sinoatrial region, atrial wall, atrioventricular band, ventricular wall and heart chambers). Similarly, the electrical model consisted of two parts with the body described by Laplace's equation and the heart using a bidomain ionic model based upon the Fitzhugh-Nagumo equations. Each region of the heart was differentiated by action potential (AP) parameters and activation wave conduction velocities, which were fitted and scaled based on previously published experimental results. ECG measurements in vivo at different electrode recording positions were then compared to the model results. The model was able to simulate action potentials, wave propagation and all the major features (P wave, R wave, T wave) of the ECG, as well as polarity of the peaks observed at each position. This model was based upon our current understanding of the structure of the normal zebrafish larval heart. Further development would enable us to incorporate features associated with the diseased heart and hence assist in the interpretation of larval zebrafish ECGs in these conditions.
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Affiliation(s)
- James Crowcombe
- School of Engineering, University of Birmingham, Birmingham, United Kingdom
| | - Sundeep Singh Dhillon
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Rhiannon Mary Hurst
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Ferenc Müller
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Attila Sík
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Edward Tarte
- School of Engineering, University of Birmingham, Birmingham, United Kingdom
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Egginton S, Hussain A, Hall-Jones J, Chaudhry B, Syeda F, Glen KE. Shear stress-induced angiogenesis in mouse muscle is independent of the vasodilator mechanism and quickly reversible. Acta Physiol (Oxf) 2016; 218:153-166. [PMID: 27261201 PMCID: PMC5082534 DOI: 10.1111/apha.12728] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/10/2015] [Accepted: 06/01/2016] [Indexed: 11/29/2022]
Abstract
AIM Is modulation of skeletal muscle capillary supply by altering blood flow due to a presumptive shear stress response per se, or dependent on the vasodilator mechanism? METHODS The response to four different vasodilators, and cotreatment with blockers of NO and prostaglandin synthesis, was compared. Femoral artery blood flow was correlated with capillary-to-fibre ratio (C:F) and protein levels of putative angiogenic compounds. RESULTS All vasodilators induced a similar increase in blood flow after 14 days, with a similar effect on C:F (1.62 ± 0.05, 1.60 ± 0.01, 1.57 ± 0.06, 1.57 ± 0.07, respectively, all P < 0.05 vs. control 1.20 ± 0.01). Concomitant inhibitors revealed differential effects on blood flow and angiogenesis, demonstrating that a similar response may have different signalling origins. The time course of this response with the most commonly used vasodilator, prazosin, showed that blood flow increased from 0.40 mL min-1 to 0.61 mL min-1 by 28 days (P < 0.05), dropped within 1 week after the cessation of treatment (0.54 mL min-1 ; P < 0.05) and returned to control levels by 6 weeks. In parallel with FBF, capillary rarefaction began within 1 week (P < 0.05), giving C:F values similar to control by 2 weeks. Of the dominant signalling pathways, prazosin decreased muscle VEGF, but increased its cognate receptor Flk-1 (both P < 0.01); levels of eNOS varied with blood flow (P < 0.05), and Ang-1 initially increased, while its receptor Tie-2 was unchanged, with only modest changes in the antiangiogenic factor TSP-1. CONCLUSION Hyperaemia-induced angiogenesis, likely in response to elevated shear stress, is independent of the vasodilator involved, with a rapid induction and quick regression following the stimulus withdrawal.
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Affiliation(s)
- S. Egginton
- School of Biomedical Sciences; University of Leeds; Leeds UK
| | - A. Hussain
- Science Department; Denefield School; Reading UK
- Centre for Cardiovascular Sciences; Medical School; University of Birmingham; Birmingham UK
| | - J. Hall-Jones
- Centre for Cardiovascular Sciences; Medical School; University of Birmingham; Birmingham UK
| | - B. Chaudhry
- Centre for Cardiovascular Sciences; Medical School; University of Birmingham; Birmingham UK
| | - F. Syeda
- Centre for Cardiovascular Sciences; Medical School; University of Birmingham; Birmingham UK
| | - K. E. Glen
- Centre for Biological Engineering; Loughborough University; Loughborough UK
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Garcia-Martinez V, Lopez Sanchez C, Hamed W, Hamed W, Hsu JH, Ferrer-Lorente R, Alshamrani M, Pizzicannella J, Vindis C, Badi I, Korte L, Voellenkle C, Niculescu LS, Massaro M, Babaeva AR, Da Silva F, Woudstra L, Berezin A, Bae MK, Del Giudice C, Bageghni SA, Krobert K, Levay M, Vignier N, Ranieri A, Magenta A, Orlandi A, Porro B, Jeon ES, Omori Y, Herold J, Barnett GA, Grochot-Przeczek A, Korpisalo P, Deffge C, Margariti A, Rong W, Maring JA, Gambardella J, Mitrofan CG, Karpinska O, Morbidelli L, Wilkinson FL, Berezin A, Kostina AS, De Mey JGR, Kumar A, Lupieri A, Pellet-Many C, Stamatiou R, Gromotowicz A, Dickhout A, Murina M, Roka-Moiia YM, Malinova L, Diaz-Canestro C, Vigliarolo T, Cuzzocrea S, Szantai A, Medic B, Cassambai S, Korda A, Revnic CR, Borile G, Diokmetzidou A, Murfitt L, Budko A, Fiordelisi A, De Wijs-Meijler DPM, Gevaert AB, Noriega De La Colina A, Benes J, Guillermo Solache Berrocal GSB, Gafarov V, Zhebel VM, Prakaschandra R, Stepien EL, Smith LE, Carluccio MA, Timasheva Y, Paci M, Dorofeyeva NA, Chimed CH, Petelina TI, Sorop O, Genis A, Parepa IR, Tscharre M, Krestjyaninov MV, Maia-Rocha C, Borges L, Sasonko ML, Kapel SS, Stam K, Sommariva E, Stojkovic S, O'reilly J, Chiva-Blanch G, Malinova L, Evtushenko A, Skopal J, Sunderland N, Gegenava T, Charnaia MA, Di Lascio N, Tarvainen SJ, Malandraki-Miller S, Uitterdijk A, Benzoni P, Ruivo E, Humphrey EJ, Arokiaraj MC, Franco D, Garcia-Lopez V, Aranega A, Lopez-Sanchez C, Franco D, Garcia-Lopez V, Aranega A, Garcia-Martinez V, Tayel S, Khader H, El-Helbawy N, Tayel S, Alrefai A, El-Barbary H, Wu JR, Dai ZK, Yeh JL, Sanjurjo-Rodriguez C, Richaud-Patin Y, Blanco FJ, Badimon L, Raya A, Cahill PA, Diomede F, Merciaro I, Trubiani O, Nahapetyan H, Swiader A, Faccini J, Boya P, Elbaz M, Zeni F, Burba I, Bertolotti M, Capogrossi MC, Pompilio G, Raucci A, Widmer-Teske R, Dutzmann J, Bauersachs J, Donde K, Daniel JM, Sedding DG, Simionescu N, Sanda GM, Carnuta MG, Stancu CS, Popescu AC, Popescu MR, Vlad A, Dimulescu DR, Sima AV, Scoditti E, Pellegrino M, Calabriso N, Carluccio MA, Storelli C, De Caterina R, Solodenkova KS, Kalinina EV, Usachiova MN, Lappalainen J, Lee-Rueckert MDEC, Kovanen PT, Biesbroek PS, Emmens RWE, Van Rossum AC, Juffermans LJM, Niessen JWM, Krijnen PAJ, Kremzer A, Samura T, Berezina T, Gronenko E, Kim MK, Park HJ, Bae SK, Sorriento D, Ciccarelli M, Vernieri E, Campiglia P, Trimarco B, Iaccarino G, Hemmings KE, Porter KE, Ainscough JF, Drinkhill MJ, Turner NA, Hiis HG, Cosson MV, Levy FO, Wieland T, Macquart C, Chatzifrangkeskou M, Evans A, Bonne G, Muchir A, Kemp E, Avkiran M, Carlomosti F, D'agostino M, Beji S, Zaccagnini G, Maimone B, Di Stefano V, De Santa F, Cordisco S, Antonini A, Ciarapica R, Dellambra E, Martelli F, Avitabile D, Capogrossi MC, Scioli MG, Bielli A, Agostinelli S, Tarquini C, Tarallo V, De Falco S, Zaninoni A, Fiorelli S, Bianchi P, Teruzzi G, Squellerio I, Turnu L, Lualdi A, Tremoli E, Cavalca V, Lee YJ, Ju ES, Choi JO, Lee GY, Lim BK, Manickam MANOJ, Jung SH, Omiya S, Otsu K, Deffge C, Nowak S, Wagner M, Braun-Dullaeus RC, Kostin S, Daniel JM, Francke A, Subramaniam S, Kanse SM, Al-Lamee K, Schofield CJ, Egginton S, Gershlick AH, Kloska D, Kopacz A, Augustyniak A, Dulak J, Jozkowicz A, Hytonen J, Halonen P, Taavitsainen J, Tarvainen S, Hiltunen T, Liimatainen T, Kalliokoski K, Knuuti J, Yla-Herttuala S, Wagner M, Weinert S, Isermann B, Lee J, Braun-Dullaeus RC, Herold J, Cochrane A, Kelaini S, Bojdo J, Vila Gonzalez M, Hu Y, Grieve D, Stitt AW, Zeng L, Xu Q, Margariti A, Reglin B, Xiang W, Nitzsche B, Maibier M, Pries AR, Vrijsen KR, Chamuleau SAJ, Verhage V, Metz CHG, Lodder K, Van Eeuwijk ECM, Van Dommelen SM, Doevendans PA, Smits AM, Goumans MJ, Sluijter JPG, Sorriento D, Bova M, Loffredo S, Trimarco B, Iaccarino G, Ciccarelli M, Appleby S, Morrell N, Baranowska-Kuczko M, Kloza M, Ambrozewicz E, Kozlowski M, Malinowska B, Kozlowska H, Monti M, Terzuoli E, Ziche M, Mahmoud AM, Jones AM, Wilkinson JA, Romero M, Duarte J, Alexander MY, Kremzer A, Berezina T, Gronenko E, Faggian G, Kostareva AA, Malashicheva AB, Leurgans TM, Nguyen TN, Irmukhamedov A, Riber LP, Mcgeogh R, Comer S, Blanco Fernandez A, Ghigo A, Blaise R, Smirnova NF, Malet N, Vincent P, Limon I, Gayral S, Hirsch E, Laffargue M, Mehta V, Zachary I, Aidonidis I, Kramkowski K, Miltyk W, Kolodziejczyk P, Gradzka A, Szemraj J, Chabielska E, Dijkgraaf I, Bitsch N, Van Hoof S, Verhaegen F, Koenen R, Hackeng TM, Roshchupkin DI, Buravleva KV, Sergienko VI, Zhernossekov DD, Rybachuk VM, Grinenko TV, Furman N, Dolotovskaya P, Shamyunov M, Denisova T, Reiner M, Akhmedov A, Keller S, Miranda M, Briand S, Barile L, Kullak-Ublick G, Luscher T, Camici G, Guida L, Magnone M, Ameri P, Lazzarini E, Fresia C, Bruzzone S, Zocchi E, Di Paola R, Cordaro M, Crupi R, Siracusa R, Campolo M, Bruschetta G, Fusco R, Pugliatti P, Esposito E, Paloczi J, Ruivo E, Gaspar R, Dinnyes A, Kobolak J, Ferdinandy P, Gorbe A, Todorovic Z, Krstic D, Savic Vujovic K, Jovicic D, Basta Jovanovic G, Radojevic Skodric S, Prostran M, Dean S, Mee CJ, Harvey KL, Hussain A, Pena C, Paltineanu B, Voinea S, Revnic F, Ginghina C, Zaglia T, Ceriotti P, Campo A, Carullo P, Armani A, Coppini R, Vida V, Olivotto I, Stellin G, Rizzuto R, De Stefani D, Sandri M, Catalucci D, Mongillo M, Soumaka E, Kloukina I, Tsikitis M, Makridakis M, Varela A, Davos C, Vlachou A, Capetanaki Y, Iqbal MM, Bennett H, Davenport B, Pinali C, Cooper G, Cartwright E, Kitmitto A, Strutynska NA, Mys LA, Sagach VF, Franco A, Sorriento D, Trimarco B, Iaccarino G, Ciccarelli M, Verzijl A, Stam K, Van Duin R, Reiss IKM, Duncker DJ, Merkus D, Shakeri H, Orije M, Leloup AJ, Van Hove CE, Van Craenenbroeck EM, De Meyer GRY, Vrints CJ, Lemmens K, Desjardins-Creapeau L, Wu R, Lamarre-Cliche M, Larochelle P, Bherer L, Girouard H, Melenovsky M, Kvasilova A, Benes J, Ruskova K, Sedmera D, Ana Barral ABV, Martin Fernandez M, Pablo Roman Garcia PRG, Juan Carlos Llosa JCLL, Manuel Naves Diaz MND, Cesar Moris CM, Jorge B Cannata-Andia JBCA, Isabel Rodriguez IR, Voevoda M, Gromova E, Maximov V, Panov D, Gagulin I, Gafarova A, Palahniuk H, Pashkova IP, Zhebel NV, Starzhynska OL, Naidoo DP, Rawojc K, Enguita FJ, Grudzien G, Cordwell SJ, White MY, Massaro M, Scoditti E, Calabriso N, Pellegrino M, Martinelli R, Gatta V, De Caterina R, Nasibullin TR, Erdman VV, Tuktarova IA, Mustafina OE, Hyttinen J, Severi S, Vorobyov GG, Sagach VF, Batmyagmar KH, Lkhagvasuren Z, Gapon LI, Musikhina NA, Avdeeva KS, Dyachkov SM, Heinonen I, Van Kranenburg M, De Beer VJ, Octavia Y, Van Geuns RJ, Van Den Meiracker AH, Van Der Velden J, Merkus D, Duncker DJ, Everson FP, Ogundipe T, Grandjean T, De Boever P, Goswami N, Strijdom H, Suceveanu AI, Suceveanu AP, Mazilu L, Tofoleanu DE, Catrinoiu D, Rohla M, Hauser C, Huber K, Wojta H, Weiss TW, Melnikova MA, Olezov NV, Gimaev RH, Khalaf H, Ruzov VI, Adao R, Mendes-Ferreira P, Santos-Ribeiro D, Rademaker M, Leite-Moreira AF, Bras-Silva C, Alvarenga LAA, Falcao RSP, Dias RR, Lacchini S, Gutierrez PS, Michel JB, Gurfinkel YUI, Atkov OYU, Teichert M, Korn C, Mogler C, Hertel S, Arnold C, Korff T, Augustin HG, Van Duin RWB, De Wijs-Meijler DPM, Verzijl A, Duncker DJ, Merkus D, D'alessandra Y, Farina FM, Casella M, Catto V, Carbucicchio C, Dello Russso A, Stadiotti I, Brambilla S, Chiesa M, Giacca M, Colombo GI, Pompilio G, Tondo C, Ahlin F, Andric T, Tihanyi D, Wojta J, Huber K, O'connell E, Butt A, Murphy L, Pennington S, Ledwidge M, Mcdonald K, Baugh J, Watson C, Suades R, Crespo J, Estruch R, Badimon L, Dyachenko A, Ryabukho V, Evtushenko V, Saushkina YU, Lishmanov YU, Smyshlyaev K, Bykov A, Popov S, Pavlyukova E, Anfinogenova Y, Szigetfu E, Kapornai B, Forizs E, Jenei ZS, Nagy Z, Merkely B, Zima E, Cai A, Dworakowski R, Gibbs T, Piper S, Jegard N, Mcdonagh T, Gegenava M, Dementieva II, Morozov YUA, Barsanti C, Stea F, Lenzarini F, Kusmic C, Faita F, Halonen PJ, Puhakka PH, Hytonen JP, Taavitsainen JM, Yla-Herttuala S, Supit EA, Carr CA, Groenendijk BCW, Gorsse-Bakker C, Panasewicz A, Sneep S, Tempel D, Van Der Giessen WJ, Duncker DJ, Rys J, Daraio C, Dell'era P, Paloczi J, Pigler J, Eder A, Ferdinandy P, Eschenhagen T, Gorbe A, Mazo MM, Amdursky N, Peters NS, Stevens MM, Terracciano CM. Poster session 2Morphogenetic mechanisms290MiR-133 regulates retinoic acid pathway during early cardiac chamber specification291Bmp2 regulates atrial differentiation through miR-130 during early heart looping formationDevelopmental genetics294Association of deletion allele of insertion/deletion polymorphism in alpha 2B adrenoceptor gene and hypertension with or without type 2 diabetes mellitus295Association of G1359A polymorphism of the endocannabinoid type 1 receptor (CNR1) with coronary artery disease (CAD) with type 2 diabetes mellitusCell growth, differentiation and stem cells - Vascular298Gamma-secretase inhibitor prevents proliferation and migration of ductus arteriosus smooth muscle cells: a role of Notch signaling in postnatal closure of ductus arteriosus299Mesenchymal stromal-like cells (MLCs) derived from induced pluripotent stem (iPS) cells: a promising therapeutic option to promote neovascularization300Sonic Hedgehog promotes mesenchymal stem cell differentiation to vascular smooth muscle cells in cardiovacsular disease301Proinflammatory cytokine secretion and epigenetic modification in endothelial cells treated LPS-GinfivalisCell death and apoptosis - Vascular304Mitophagy acts as a safeguard mechanism against human vascular smooth muscle cell apoptosis induced by atherogenic lipidsTranscriptional control and RNA species - Vascular307MicroRNA-34a role in vascular calcification308Local delivery of a miR-146a inhibitor utilizing a clinically applicable approach attenuates neointima formation after vascular injury309Long noncoding RNA landscape of hypoxic endothelial cells310Specific circulating microRNAs levels associate with hypertension, hyperglycemia and dysfunctional HDL in acute coronary syndrome patientsCytokines and cellular inflammation - Vascular313Phosphodiesterase5A up-regulation in vascular endothelium under pro-inflammatory conditions: a newly disclosed anti-inflammatory activity for the omega-3polyunsaturated aatty acid docosahexaenoic acid314Cardiovascular risk modifying with extra-low dose anticytokine drugs in rhematoid arthritis315Conversion of human M-CSF macrophages into foam cells reduces their proinflammatory responses to classical M1-polarizing activation316Lymphocytic myocarditis coincides with increased plaque inflammation and plaque hemorrhage in coronary arteries, facilitating myocardial infarction317Serum osteoprotegerin level predictsdeclined numerous of circulating endothelial- derived and mononuclear-derived progenitor cells in patients with metabolic syndromeGrowth factors and neurohormones - Vascular320Effect of gastrin-releasing peptide (GRP) on vascular inflammationSignal transduction - Heart323A new synthetic peptide regulates hypertrophy in vitro through means of the inhibition of nfkb324Inducible fibroblast-specific knockout of p38 alpha map kinase is cardioprotective in a mouse model of isoproterenol-induced cardiac hypertrophy325Regulation of beta-adrenoceptor-evoked inotropic responses by inhibitory G protein, adenylyl cyclase isoforms 5 and 6 and phosphodiesterases326Binding to RGS3 and stimulation of M2 muscarinic acetylcholine receptors modulates the substrate specificity of p190RhoGAP in cardiac myocytes327Cardiac regulation of post-translational modifications, parylation and deacetylation in LMNA dilated cardiomyopathy mouse model328Beta-adrenergic regulation of the b56delta/pp2a holoenzyme in cardiac myocytes through b56delta phosphorylation at serine 573Nitric oxide and reactive oxygen species - Vascular331Oxidative stress-induced miR-200c disrupts the regulatory loop among SIRT1, FOXO1 and eNOS332Antioxidant therapy prevents oxidative stress-induced endothelial dysfunction and Enhances Wound Healing333Morphological and biochemical characterization of red blood cell in coronary artery diseaseCytoskeleton and mechanotransduction - Heart336Novel myosin activator, JSH compounds, increased myocardial contractility without chronotropic effect in ratsExtracellular matrix and fibrosis - Vascular339Ablation of Toll-like receptor 9 causes cardiac rupture after myocardial infarction by attenuating proliferation and differentiation of cardiac fibroblasts340Altered vascular remodeling in the mouse hind limb ischemia model in Factor VII activating protease (FSAP) deficiencyVasculogenesis, angiogenesis and arteriogenesis343Pro-angiogenic effects of proly-hydroxylase inhibitors and their potential for use in a novel strategy of therapeutic angiogenesis for coronary total occlusion344Nrf2 drives angiogenesis in transcription-independent manner: new function of the master regulator of oxidative stress response345Angiogenic gene therapy, despite efficient vascular growth, is not able to improve muscle function in normoxic or chronically ischemic rabbit hindlimbs -role of capillary arterialization and shunting346Effect of PAR-1 inhibition on collateral vessel growth in the murine hind limb model347Quaking is a key regulator of endothelial cell differentiation, neovascularization and angiogenesis348"Emerging angiogenesis" in the chick chorioallantoic membrane (CAM). An in vivo study349Exosomes from cardiomyocyte progenitor cells and mesenchymal stem cells stimulate angiogenesis in vitro and in vivo via EMMPRINEndothelium352Reciprocal regulation of GRK2 and bradykinin receptor stimulation modulate Ca2+ intracellular level in endothelial cells353The roles of bone morphogenetic proteins 9 and 10 in endothelial inflammation and atherosclerosis354The contribution of GPR55 to the L-alpha-lysophosphatidylinositol-induced vasorelaxation in isolated human pulmonary arteries355The endothelial protective ACE inhibitor Zofenoprilat exerts anti-inflammatory activities through H2S production356A new class of glycomimetic drugs to prevent free fatty acid-induced endothelial dysfunction357Endothelial progenitor cells to apoptotic endothelial cell-derived microparticles ration differentiatesas preserved from reduced ejection fractionheart failure358Proosteogenic genes are activated in endothelial cells of patients with thoracic aortic aneurysm359Endothelin ETB receptors mediate relaxing responses to insulin in pericardial resistance arteries from patients with cardiovascular disease (CVD)Smooth muscle and pericytes362CX3CR1 positive myeloid cells regulate vascular smooth muscle tone by inducing calcium oscillations via activation of IP3 receptors363A novel function of PI3Kg on cAMP regulation, role in arterial wall hyperplasia through modulation of smooth muscle cells proliferation364NRP1 and NRP2 play important roles in the development of neointimal hyperplasia in vivo365Azithromycin induces autophagy in aortic smooth muscle cellsCoagulation, thrombosis and platelets368The real time in vivo evaluation of platelet-dependent aldosterone prothrombotic action in mice369Development of a method for in vivo detection of active thrombi in mice370The antiplatelet effects of structural analogs of the taurine chloramine371The influence of heparin anticoagulant drugs on functional state of human platelets372Regulation of platelet aggregation and adenosine diphosphate release by d dimer in acute coronary syndrome (in vitro study)Oxygen sensing, ischaemia and reperfusion375Sirtuin 5 mediates brain injury in a mouse model of cerebral ischemia-reperfusion376Abscisic acid: a new player in cardiomyocyte protection from ischaemia?377Protective effects of ultramicronized palmitoylethanolamide (PEA-um) in myocardial ischaemia and reperfusion injury in vivo378Identification of stem cell-derived cardiomyocytes using cardiac specific markers and additional testing of these cells in simulated ischemia/reperfusion system379Single-dose intravenous metformin treatment could afford significant protection of the injured rat kidney in an experimental model of ischemia-reperfusion380Cardiotoxicity of long acting muscarinic receptor antagonists used for chronic obstructive pulmonary disease381Dependence antioxidant potential on the concentration of amino acids382The impact of ischemia-reperfusion on physiological parameters,apoptosis and ultrastructure of rabbit myocardium with experimental aterosclerosisMitochondria and energetics385MicroRNA-1 dependent regulation of mitochondrial calcium uniporter (MCU) in normal and hypertrophied hearts386Mitochondrial homeostasis and cardioprotection: common targets for desmin and aB-crystallin387Overexpression of mitofusin-2 (Mfn2) and associated mitochondrial dysfunction in the diabetic heart388NO-dependent prevention of permeability transition pore (MPTP) opening by H2S and its regulation of Ca2+ accumulation in rat heart mitochondria389G protein coupled receptor kinase 2 (GRK2) is fundamental in recovering mitochondrial morphology and function after exposure to ionizing radiation (IR)Gender issues392Sex differences in pulmonary vascular control; focus on the nitric oxide pathwayAging395Heart failure with preserved ejection fraction develops when feeding western diet to senescence-accelerated mice396Cardiovascular markers as predictors of cognitive decline in elderly hypertensive patients397Changes in connexin43 in old rats with volume overload chronic heart failureGenetics and epigenetics400Calcium content in the aortic valve is associated with 1G>2G matrix metalloproteinase 1 polymorphism401Neuropeptide receptor gene s (NPSR1) polymorphism and sleep disturbances402Endothelin-1 gene Lys198Asn polymorphism in men with essential hypertension complicated and uncomplicated with chronic heart failure403Association of common polymorphisms of the lipoprotein lipase and pon1 genes with the metabolic syndrome in a sample of community participantsGenomics, proteomics, metabolomics, lipidomics and glycomics405Gene expression quantification using multiplexed color-coded probe pairs to determine RNA content in sporadic cardiac myxoma406Large-scale phosphorylation study of the type 2 diabetic heart subjected to ischemia / reperfusion injury407Transcriptome-based identification of new anti-inflammatory properties of the olive oil hydroxytyrosol in vascular endothelial cell under basal and proinflammatory conditions408Gene polymorphisms combinations and risk of myocardial infarctionComputer modelling, bioinformatics and big data411Comparison of the repolarization reserve in three state-of-the-art models of the human ventricular action potentialMetabolism, diabetes mellitus and obesity414Endothelial monocyte-activating polypeptide-II improves heart function in type -I Diabetes mellitus415Admission glucose level is independent predictor of impaired left ventricular function in patients with acute myocardial infarction: a two dimensional speckle-tracking echocardiography study416Association between biochemical markers of lipid profile and inflammatory reaction and stiffness of the vascular wall in hypertensive patients with abdominal obesity417Multiple common co-morbidities produce left ventricular diastolic dysfunction associated with coronary microvascular dysfunction, oxidative stress and myocardial stiffening418Investigating the cardiovascular effects of antiretroviral drugs in a lean and high fat/sucrose diet rat model of obesity419Statins in the treatment of non-alcoholic steatohepatitis (NASH). Our experience from a 2-year prospective study in Constanta County, Romania420Epicardial adipose tissue as a predictor of cardiovascular outcome in patients with ACS undergoing PCI?Arterial and pulmonary hypertension423Dependence between heart rhythm disorers and ID polymorphism of ACE gene in hypertensive patients424Molecular mechanisms underlying the beneficial effects of Urocortin 2 in pulmonary arterial hypertension425Inhibition of TGf-b axis and action of renin-angiotensin system in human ascending aorta aneurysms426Early signs of microcirculation and macrocirculation abnormalities in prehypertension427Vascular smooth muscle cell-expressed Tie-2 controls vascular tone428Cardiac and vascular remodelling in the development of chronic thrombo-embolic pulmonary hypertension in a novel swine modelBiomarkers431Arrhythmogenic cardiomyopathy: a new, non invasive biomarker432Can circulating microRNAs distinguish type 1 and type 2 myocardial infarction?433Design of a high-throughput multiplex proteomics assay to identify left ventricular diastolic dysfunction in diabetes434Monocyte-derived and P-selectin-carrying microparticles are differently modified by a low fat diet in patients with cardiovascular risk factors who will and who will not develop a cardiovascular event435Red blood cell distribution width assessment by polychromatic interference microscopy of thin films in chronic heart failure436Invasive and noninvasive evaluation of quality of radiofrequency-induced cardiac denervation in patients with atrial fibrillation437The effect of therapeutic hypothermia on the level of brain derived neurotrophic factor (BDNF) in sera following cardiopulmonary resustitation438Novel biomarkers to predict outcome in patients with heart failure and severe aortic stenosis439Biological factors linking depression and anxiety to cardiovascular disease440Troponins and myoglobin dynamic at coronary arteries graftingInvasive, non-invasive and molecular imaging443Diet composition effects on the genetic typing of the mouse ob mutation: a micro-ultrasound characterization of cardiac function, macro and micro circulation and liver steatosis444Characterization of pig coronary and rabbit aortic lesions using IV-OCT quantitative analysis: correlations with histologyGene therapy and cell therapy447Enhancing the survival and angiogenic potential of mouse atrial mesenchymal cells448VCAM-1 expression in experimental myocardial infarction and its relation to bone marrow-derived mononuclear cell retentionTissue engineering451Advanced multi layered scaffold that increases the maturity of stem cell-derived human cardiomyocytes452Response of engineered heart tissue to simulated ischemia/reperfusion in the presence of acute hyperglycemic conditions453Serum albumin hydrogels prevent de-differentiation of neonatal cardiomyocytes454A novel paintbrush technique for transfer of low viscosity ultraviolet light curable cyan methacrylate on saline immersed in-vitro sheep heart. Cardiovasc Res 2016. [DOI: 10.1093/cvr/cvw149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Barnett GA, Schofield CJ, Al-Lamee K, Casaretto M, Arndt S, Egginton S, Gershlick AH. 3 Angiogenesis as a therapeutic option for untreatable CTO. Heart 2016. [DOI: 10.1136/heartjnl-2016-309588.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Renwick NC, Egginton S, Ferguson C. Reductions in Cardiovascular and Metabolic Demands During Work Rate Matched Eccentric Stepping Exercise. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000486106.88609.62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Egginton S, Campbell HA. Cardiorespiratory responses in an Antarctic fish suggest limited capacity for thermal acclimation. ACTA ACUST UNITED AC 2016; 219:1283-6. [PMID: 26944499 DOI: 10.1242/jeb.130963] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 02/16/2016] [Indexed: 01/09/2023]
Abstract
Polar fishes are at high risk from increasing seawater temperatures. Characterising the physiological responses to such changes may both clarify mechanisms that permit life under extreme conditions and identify limitations in the response to continued global warming. We hypothesised that Notothenia coriiceps would show physiological compensation after an acute exposure to 5°C, and following 6 weeks warm acclimation, compared with ambient temperature (0°C). However, initial tachycardia (22.4±2.8 versus 12.8±1.1 min(-1); P<0.01) was not reversed by acclimation (21.0±1.9 min(-1)). Hyperventilation (45.5±3.1 versus 21.4±2.4 breaths min(-1); P<0.001) showed a modest reduction following acclimation (38.0±2.9 min(-1); P<0.05), while resting oxygen consumption (0.52±0.08 mmol kg(-1) h(-1)) was acutely increased at 5°C (1.07±0.10 mmol kg(-1) h(-1); P<0.001) but unchanged with acclimation. Autonomic blockade showed initial responses were mainly of vagal origin, with little subsequent withdrawal or recovery in long-term heart rate variability after 6 weeks. Given the limited cardiorespiratory capacity to withstand sustained warming, effective physiological compensation probably requires a more prolonged acclimation period.
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Affiliation(s)
- Stuart Egginton
- Multidisciplinary Cardiovascular Research Centre, School of Biomedical Sciences, University of Leeds, Garstang 5.64, Clarendon Way, Leeds LS2 9JT, UK
| | - Hamish A Campbell
- School of the Environment, Charles Darwin University, Darwin, NT 0909, Australia
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Davidsen PK, Turan N, Egginton S, Falciani F. Multilevel functional genomics data integration as a tool for understanding physiology: a network biology perspective. J Appl Physiol (1985) 2016; 120:297-309. [DOI: 10.1152/japplphysiol.01110.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 11/04/2015] [Indexed: 01/30/2023] Open
Abstract
The overall aim of physiological research is to understand how living systems function in an integrative manner. Consequently, the discipline of physiology has since its infancy attempted to link multiple levels of biological organization. Increasingly this has involved mathematical and computational approaches, typically to model a small number of components spanning several levels of biological organization. With the advent of “omics” technologies, which can characterize the molecular state of a cell or tissue (intended as the level of expression and/or activity of its molecular components), the number of molecular components we can quantify has increased exponentially. Paradoxically, the unprecedented amount of experimental data has made it more difficult to derive conceptual models underlying essential mechanisms regulating mammalian physiology. We present an overview of state-of-the-art methods currently used to identifying biological networks underlying genomewide responses. These are based on a data-driven approach that relies on advanced computational methods designed to “learn” biology from observational data. In this review, we illustrate an application of these computational methodologies using a case study integrating an in vivo model representing the transcriptional state of hypoxic skeletal muscle with a clinical study representing muscle wasting in chronic obstructive pulmonary disease patients. The broader application of these approaches to modeling multiple levels of biological data in the context of modern physiology is discussed.
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Affiliation(s)
- Peter K. Davidsen
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Nil Turan
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom; and
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Francesco Falciani
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
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Tikkanen E, Haverinen J, Egginton S, Hassinen M, Vornanen M. Effects of prolonged anoxia on electrical activity of the heart in Crucian carp (Carassius carassius). J Exp Biol 2016; 220:445-454. [DOI: 10.1242/jeb.145177] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 11/15/2016] [Indexed: 01/08/2023]
Abstract
The effects of sustained anoxia on cardiac electrical excitability were examined in the anoxia-tolerant Crucian carp (Carassius carassius). The electrocardiogram (ECG) and expression of excitation-contraction coupling genes were studied in fish acclimatised to normoxia in summer (+18°C) or winter (+2°C), and in winter fish after 1, 3 and 6 weeks of anoxia. Anoxia induced a sustained bradycardia from a heart rate of 10.3±0.77 to 4.1±0.29 bpm (P<0.05) after 5 weeks, and heart rate slowly recovered to control levels when oxygen was restored. Heart rate variability greatly increased under anoxia, and completely recovered under re-oxygenation. The RT interval increased from 2.8±0.34 s in normoxia to 5.8±0.44 s under anoxia (P<0.05), which reflects a doubling of the ventricular action potential (AP) duration. Acclimatisation to winter induced extensive changes in gene expression relative to summer-acclimatised fish, including depression in those coding for the sarcoplasmic reticulum calcium pump (Serca2-q2) and ATP-sensitive K+ channels (Kir6.2) (P<0.05). Genes of delayed rectifier K+ (kcnh6) and Ca2+ channels (cacna1c) were up-regulated in winter fish (P<0.05). In contrast, the additional challenge of anoxia caused only minor changes in gene expression, e.g. depressed expression of Kir2.2b K+ channel gene (kcnj12b), whereas expression of Ca2+ (cacna1a, -c and –g) and Na+ channel genes (scn4a and scn5a) were not affected. These data suggest that low temperature pre-conditions the Crucian carp heart for winter anoxia, whereas sustained anoxic bradycardia and prolongation of AP duration are directly induced by oxygen shortage without major changes in gene expression.
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Affiliation(s)
- Elisa Tikkanen
- University of Eastern Finland, Department of Environmental and Biological Sciences, Finland
| | - Jaakko Haverinen
- University of Eastern Finland, Department of Environmental and Biological Sciences, Finland
| | | | - Minna Hassinen
- University of Eastern Finland, Department of Environmental and Biological Sciences, Finland
| | - Matti Vornanen
- University of Eastern Finland, Department of Environmental and Biological Sciences, Finland
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Abstract
The role of capillaries is to serve as the interface for delivery of oxygen and removal of metabolites to/from tissues. During the past decade there has been a proliferation of studies that have advanced our understanding of angiogenesis, demonstrating that tissue capillary supply is under strict control during health but poorly controlled in disease, resulting in either excessive capillary growth (pathological angiogenesis) or losses in capillarity (rarefaction). Given that skeletal muscle comprises nearly 40% of body mass in humans, skeletal muscle capillary density has a significant impact on metabolism, endocrine function, and locomotion and is tightly regulated at many different levels. Skeletal muscle is also high adaptable and thus one of the few organ systems that can be experimentally manipulated (e.g., by exercise) to study physiological regulation of angiogenesis. This review will focus on the methodological concerns that have arisen in determining skeletal muscle capillarity and highlight the concepts that are reshaping our understanding of the angio-adaptation process. We also summarize selected new findings (physical influences, molecular changes, and ultrastructural rearrangement of capillaries) that identify areas of future research with the greatest potential to expand our understanding of how angiogenesis is normally regulated, and that may also help to better understand conditions of uncontrolled (pathological) angiogenesis.
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Affiliation(s)
- I Mark Olfert
- Center for Cardiovascular and Respiratory Sciences and Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, West Virginia;
| | - Oliver Baum
- Institute of Anatomy, University of Bern, Bern, Switzerland
| | - Ylva Hellsten
- Integrative Physiology Group, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark; and
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
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Hauton D, Al-Shammari A, Gaffney EA, Egginton S. Maternal hypoxia decreases capillary supply and increases metabolic inefficiency leading to divergence in myocardial oxygen supply and demand. PLoS One 2015; 10:e0127424. [PMID: 26030353 PMCID: PMC4452690 DOI: 10.1371/journal.pone.0127424] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 04/15/2015] [Indexed: 12/04/2022] Open
Abstract
Maternal hypoxia is associated with a decrease in left ventricular capillary density while cardiac performance is preserved, implying a mismatch between metabolism and diffusive exchange. We hypothesised this requires a switch in substrate metabolism to maximise efficiency of ATP production from limited oxygen availability. Rat pups from pregnant females exposed to hypoxia (FIO2=0.12) at days 10-20 of pregnancy were grown to adulthood and working hearts perfused ex vivo. 14C-labelled glucose and 3H-palmitate were provided as substrates and metabolism quantified from recovery of 14CO2 and 3H2O, respectively. Hearts of male offspring subjected to Maternal Hypoxia showed a 20% decrease in cardiac output (P<0.05), despite recording a 2-fold increase in glucose oxidation (P<0.01) and 2.5-fold increase (P<0.01) in palmitate oxidation. Addition of insulin to Maternal Hypoxic hearts, further increased glucose oxidation (P<0.01) and suppressed palmitate oxidation (P<0.05), suggesting preservation in insulin signalling in the heart. In vitro enzyme activity measurements showed that Maternal Hypoxia increased both total and the active component of cardiac pyruvate dehydrogenase (both P<0.01), although pyruvate dehydrogenase sensitivity to insulin was lost (NS), while citrate synthase activity declined by 30% (P<0.001) and acetyl-CoA carboxylase activity was unchanged by Maternal Hypoxia, indicating realignment of the metabolic machinery to optimise oxygen utilisation. Capillary density was quantified and oxygen diffusion characteristics examined, with calculated capillary domain area increased by 30% (P<0.001). Calculated metabolic efficiency decreased 4-fold (P<0.01) for Maternal Hypoxia hearts. Paradoxically, the decline in citrate synthase activity and increased metabolism suggest that the scope of individual mitochondria had declined, rendering the myocardium potentially more sensitive to metabolic stress. However, decreasing citrate synthase may be essential to preserve local PO2, minimising regions of hypoxia and hence maximising the area of myocardium able to preserve cardiac output following maternal hypoxia.
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Affiliation(s)
- David Hauton
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, United Kingdom
- * E-mail:
| | - Abdullah Al-Shammari
- Department of Mathematics, Faculty of Sciences, Kuwait University, Kuwait City, Kuwait
| | - Eamonn A. Gaffney
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom
| | - Stuart Egginton
- School of Biomedical Science, University of Leeds, Leeds, United Kingdom
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Ahmad S, Wang K, Egginton S, Hewett PW, Ahmed A. Hydrogen sulphide rescues preeclampsia-like phenotype aggravated by high sFlt-1 in placenta growth factor (PlGF) deficiency. Nitric Oxide 2015. [DOI: 10.1016/j.niox.2015.02.066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
This collection of papers is based on talks presented at the IUPS meeting in Birmingham, UK last summer, in a symposium as part of the ESM & EVBO program, sponsored by the British Microcirculation Society and Microcirculation. In this issue we discuss new insights into the control of angiogenesis, including regulation of different aspects of endothelial cell biology by the tissue stroma, during inflammatory disease, and active remodelling of the microcirculation. We address a variety of signalling modes that determine the endothelial responses to pro-angiogenic stimuli, including necessary synergy among different pathways and processes. We present an update of recent developments, and identify some areas where significant progress will likely occur.
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Wragg JW, Durant S, McGettrick HM, Sample KM, Egginton S, Bicknell R. Shear stress regulated gene expression and angiogenesis in vascular endothelium. Microcirculation 2015; 21:290-300. [PMID: 24471792 DOI: 10.1111/micc.12119] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 01/22/2014] [Indexed: 01/13/2023]
Abstract
The behavior of vascular EC is greatly altered in sites of pathological angiogenesis, such as a developing tumor or atherosclerotic plaque. Until recently it was thought that this was largely due to abnormal chemical signaling, i.e., endothelial cell chemo transduction, at these sites. However, we now demonstrate that the shear stress intensity encountered by EC can have a profound impact on their gene expression and behavior. We review the growing body of evidence suggesting that mechanotransduction, too, is a major regulator of pathological angiogenesis. This fits with the evolving story of physiological angiogenesis, where a combination of metabolic and mechanical signaling is emerging as the probable mechanism by which tight feedback regulation of angiogenesis is achieved in vivo.
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Affiliation(s)
- Joseph W Wragg
- Angiogenesis Group, Centre for Cardiovascular Sciences, Institute for Biomedical Research, Schools of Immunity and Infection and Cancer Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
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Bosutti A, Egginton S, Barnouin Y, Ganse B, Rittweger J, Degens H. Local capillary supply in muscle is not determined by local oxidative capacity. J Exp Biol 2015; 218:3377-80. [DOI: 10.1242/jeb.126664] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 09/04/2015] [Indexed: 11/20/2022]
Abstract
It is thought that the prime determinant of global muscle capillary density is the mean oxidative capacity. However, feedback control during maturational growth or adaptive remodelling of local muscle capillarisation is likely more complex than simply matching O2 supply and demand in response to integrated tissue function. We tested the hypothesis that the maximal oxygen consumption (MO2max) supported by a capillary is relatively constant, and independent of the volume of tissue supplied (capillary domain). We demonstrate that local MO2max assessed by succinate dehydrogenase histochemistry 1) varied more than 100-fold between individual capillaries and 2) was positively correlated to capillary domain area in both human vastus lateralis (R=0.750, P<0.001) and soleus (R=0.697, P<0.001) muscles. This suggests that, in contrast to common assumptions, capillarisation is not primarily dictated by local oxidative capacity, but rather by factors such as fibre size, or consequences of differences in fibre size such as substrate delivery/metabolite removal.
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Affiliation(s)
- Alessandra Bosutti
- Department of Medical, Surgery and Health Sciences, University of Trieste, Trieste, Italy
- School of Healthcare Science, Manchester Metropolitan University, United Kingdom
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, United Kingdom
| | - Yoann Barnouin
- School of Healthcare Science, Manchester Metropolitan University, United Kingdom
| | - Bergita Ganse
- Institute of Aerospace Medicine, German Aerospace Centre, Linder Höhe, 51147 Cologne, Germany
| | - Jörn Rittweger
- Institute of Aerospace Medicine, German Aerospace Centre, Linder Höhe, 51147 Cologne, Germany
| | - Hans Degens
- School of Healthcare Science, Manchester Metropolitan University, United Kingdom
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Hauton D, Winter J, Al-Shammari AA, Gaffney EA, Evans RD, Egginton S. Changes to both cardiac metabolism and performance accompany acute reductions in functional capillary supply. Biochim Biophys Acta Gen Subj 2014; 1850:681-90. [PMID: 25529297 DOI: 10.1016/j.bbagen.2014.12.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 11/14/2014] [Accepted: 12/12/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND The relative importance of arteriole supply or ability to switch between substrates to preserve cardiac performance is currently unclear, but may be critically important in conditions such as diabetes. METHODS Metabolism of substrates was measured before and after infusion of polystyrene microspheres in the perfused working heart to mimic random capillary loss due to microvascular disease. The effect of acute loss of functional capillary supply on palmitate and glucose metabolism together with function was quantified, and theoretical tissue oxygen distribution calculated from histological samples and ventricular VO(2) estimated. RESULTS Microsphere infusion led to a dose-dependent decrease in rate-pressure product (RPP) and oxygen consumption (P<0.001). Microsphere infusion also increased work/unit oxygen consumption of hearts ('efficiency') by 25% (P<0.01). When corrected for cardiac work palmitate oxidation remained tightly coupled to very low workloads (RPP<2500 mmHg/min), illustrating a high degree of metabolic control. Arteriole occlusion by microspheres decreased the density of patent capillaries (P<0.001) and correspondingly increased the average capillary supply area by 40% (P<0.01). Calculated rates of oxygen consumption declined from 16.6±7.2 ml/100 ml/min to 12.4±9 ml/100 ml/min following arteriole occlusion, coupled with increases in size of regions of myocardial hypoxia (Control=22.0% vs. Microspheres=42.2%). CONCLUSIONS Cardiac mechanical performance is very sensitive to arteriolar blockade, but metabolite switching from fatty acid to glucose utilisation may also support cardiac function in regions of declining PO(2). GENERAL SIGNIFICANCE Preserving functional capillary supply may be critical for maintenance of cardiac function when metabolic flexibility is lost, as in diabetes.
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Affiliation(s)
- David Hauton
- School of Food Science and Nutrition, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom.
| | - James Winter
- Cardiovascular Physiology, The Rayne Institute, King's College London, London SE1 7EH, United Kingdom
| | - Abdullah A Al-Shammari
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG, United Kingdom; Department of Mathematics, Faculty of Sciences, Kuwait University, P.O. Box 5969, Khaldiya 13060, Kuwait
| | - Eamonn A Gaffney
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG, United Kingdom
| | - Rhys D Evans
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, South Parks Road, Oxford OX1 3PT, United Kingdom
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Clarendon Way, Leeds LS2 9JT, United Kingdom
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