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Degens H, Paudyal A, Kwakkel G, Slevin M, Maas H. Stroke-induced excess in capillarization relative to oxidative capacity in rats is muscle specific. Physiol Rep 2024; 12:e16153. [PMID: 39016169 PMCID: PMC11253024 DOI: 10.14814/phy2.16153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 07/08/2024] [Accepted: 07/08/2024] [Indexed: 07/18/2024] Open
Abstract
Stroke is not only associated with muscle weakness, but also associated with reduced muscle fatigue resistance and reduced desaturation during exercise that may be caused by a reduced oxidative capacity and/or microvasculature. Therefore, the objective of the present study was to determine the effects of stroke on muscle mass, fiber size and shape, capillarization and oxidative capacity of the rat m. extensor carpi radialis (ECR) and m. flexor carpi ulnaris (FCU) after a photothrombotic stroke in the forelimb region of the primary sensorimotor cortex. The main observation of the present study was that 4 weeks after induction of stroke there were no significant changes in muscle fiber size and shape. Although there was no significant capillary rarefaction, there was some evidence for remodeling of the capillary bed as reflected by a reduced heterogeneity of capillary spacing (p = 0.006) that may result in improved muscle oxygenation. In the ECR, but not in the FCU, this was accompanied by reduction in muscle fiber oxidative capacity as reflected by reduced optical density of sections stained for succinate dehydrogenase (p = 0.013). The reduced oxidative capacity and absence of significant capillary rarefaction resulted in a capillary to fiber ratio per unit of oxidative capacity that was higher after stroke in the ECR (p = 0.01), but not in the FCU. This suggests that at least during the early stages, stroke is not necessarily accompanied by muscle fiber atrophy, and that stroke-induced reductions in oxidative capacity resulting in relative excess of capillarization are muscle specific.
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Affiliation(s)
- Hans Degens
- Department of Life SciencesManchester Metropolitan UniversityManchesterUK
- Institute of Sport Science and InnovationsLithuanian Sports UniversityKaunasLithuania
| | - Arjun Paudyal
- Department of Life SciencesManchester Metropolitan UniversityManchesterUK
- Department of Human Movement Sciences, Faculty of Behavioural and Movement SciencesAmsterdam Movement Sciences, Vrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Gert Kwakkel
- Department of Rehabilitation MedicineAmsterdam Movement Sciences, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit AmsterdamAmsterdamThe Netherlands
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of MedicineNorthwestern UniversityChicagoIllinoisUSA
- Department of NeurorehabilitationAmsterdam Rehabilitation Research CentreAmsterdamThe Netherlands
| | - Mark Slevin
- Department of Life SciencesManchester Metropolitan UniversityManchesterUK
- The George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu MuresTargu MuresTransylvaniaRomania
| | - Huub Maas
- Department of Human Movement Sciences, Faculty of Behavioural and Movement SciencesAmsterdam Movement Sciences, Vrije Universiteit AmsterdamAmsterdamThe Netherlands
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2
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Wagner PD. Blood Gas Transport: Implications for O2 and CO2 Exchange in Lungs and Tissues. Semin Respir Crit Care Med 2023; 44:584-593. [PMID: 37567252 DOI: 10.1055/s-0043-1771161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2023]
Abstract
The well-known ways in which O2 and CO2 (and other gases) are carried in the blood were presented in the preceding chapter. However, what the many available texts about O2 and CO2 transport do not emphasize is why knowing how gases are carried in blood matters, and this second, companion, article specifically addresses that critical aspect of gas exchange physiology. During gas exchange, both at the lungs and in the peripheral tissues, it is the shapes and the slopes of the O2 and CO2 binding curves that explain almost all of the behaviors of each gas and the quantitative differences observed between them. This conclusion is derived from first principle considerations of the gas exchange processes. Dissociation curve shape and slope differences explain most of the differences between O2 and CO2 in both diffusive exchange in the lungs and tissues and convective exchange/transport in, and between, the lungs and tissues. In fact, each of the chapters in this volume describes physiological behavior that depends more or less directly on the dissociation curves of O2 and CO2.
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Affiliation(s)
- Peter D Wagner
- Department of Medicine, University of California San Diego, La Jolla, California
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3
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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] [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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4
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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] [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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5
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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] [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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6
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Sun N, Ning B, Bruce AC, Cao R, Seaman SA, Wang T, Fritsche-Danielson R, Carlsson LG, Peirce SM, Hu S. In vivo imaging of hemodynamic redistribution and arteriogenesis across microvascular network. Microcirculation 2019; 27:e12598. [PMID: 31660674 DOI: 10.1111/micc.12598] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 10/17/2019] [Accepted: 10/21/2019] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Arteriogenesis is an important mechanism that contributes to restoration of oxygen supply in chronically ischemic tissues, but remains incompletely understood due to technical limitations. This study presents a novel approach for comprehensive assessment of the remodeling pattern in a complex microvascular network containing multiple collateral microvessels. METHODS We have developed a hardware-software integrated platform for quantitative, longitudinal, and label-free imaging of network-wide hemodynamic changes and arteriogenesis at the single-vessel level. By ligating feeding arteries in the mouse ear, we induced network-wide hemodynamic redistribution and localized arteriogenesis. The utility of this technology was demonstrated by studying the influence of obesity on microvascular arteriogenesis. RESULTS Simultaneously monitoring the remodeling of competing collateral arterioles revealed a new, inverse relationship between initial vascular resistance and extent of arteriogenesis. Obese mice exhibited similar remodeling responses to lean mice through the first week, including diameter increase and flow upregulation in collateral arterioles. However, these gains were subsequently lost in obese mice. CONCLUSIONS Capable of label-free, comprehensive, and dynamic quantification of structural and functional changes in the microvascular network in vivo, this platform opens up new opportunities to study the mechanisms of microvascular arteriogenesis, its implications in diseases, and approaches to pharmacologically rectify microvascular dysfunction.
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Affiliation(s)
- Naidi Sun
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Bo Ning
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Anthony C Bruce
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Rui Cao
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Scott A Seaman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Tianxiong Wang
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | | | - Leif G Carlsson
- Bioscience Heart Failure, Cardiovascular, Renal and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Shayn M Peirce
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Song Hu
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
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7
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Beretta E, Grasso GS, Forcaia G, Sancini G, Miserocchi G. Differences in alveolo-capillary equilibration in healthy subjects on facing O 2 demand. Sci Rep 2019; 9:16693. [PMID: 31723148 PMCID: PMC6854051 DOI: 10.1038/s41598-019-52679-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 10/18/2019] [Indexed: 12/02/2022] Open
Abstract
Oxygen diffusion across the air-blood barrier in the lung is commensurate with metabolic needs and ideally allows full equilibration between alveolar and blood partial oxygen pressures. We estimated the alveolo-capillary O2 equilibration in 18 healthy subjects at sea level at rest and after exposure to increased O2 demand, including work at sea level and on hypobaric hypoxia exposure at 3840 m (PA ~ 50 mmHg). For each subject we estimated O2 diffusion capacity (DO2), pulmonary capillary blood volume (Vc) and cardiac output ([Formula: see text]). We derived blood capillary transit time [Formula: see text] and the time constant of the equilibration process ([Formula: see text], β being the slope of the hemoglobin dissociation curve). O2 equilibration at the arterial end of the pulmonary capillary was defined as [Formula: see text]. Leq greately differed among subjects in the most demanding O2 condition (work in hypoxia): lack of full equilibration was found to range from 5 to 42% of the alveolo-capillary PO2 gradient at the venous end. The present analysis proves to be sensible enough to highlight inter-individual differences in alveolo-capillary equilibration among healthy subjects.
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Affiliation(s)
- Egidio Beretta
- Dipartimento di Medicina e Chirurgia, Ambulatorio di Fisiologia Clinica e dello Sport, Scuola di Specializzazione in Medicina dello Sport, Università di Milano-Bicocca, Via Cadore, 48, 20900, Monza, Italy.
| | - Gabriele Simone Grasso
- Dipartimento di Medicina e Chirurgia, Ambulatorio di Fisiologia Clinica e dello Sport, Scuola di Specializzazione in Medicina dello Sport, Università di Milano-Bicocca, Via Cadore, 48, 20900, Monza, Italy
| | - Greta Forcaia
- Dipartimento di Medicina e Chirurgia, Ambulatorio di Fisiologia Clinica e dello Sport, Scuola di Specializzazione in Medicina dello Sport, Università di Milano-Bicocca, Via Cadore, 48, 20900, Monza, Italy
| | - Giulio Sancini
- Dipartimento di Medicina e Chirurgia, Ambulatorio di Fisiologia Clinica e dello Sport, Scuola di Specializzazione in Medicina dello Sport, Università di Milano-Bicocca, Via Cadore, 48, 20900, Monza, Italy
| | - Giuseppe Miserocchi
- Dipartimento di Medicina e Chirurgia, Ambulatorio di Fisiologia Clinica e dello Sport, Scuola di Specializzazione in Medicina dello Sport, Università di Milano-Bicocca, Via Cadore, 48, 20900, Monza, Italy
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8
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Hendrickse P, Degens H. The role of the microcirculation in muscle function and plasticity. J Muscle Res Cell Motil 2019; 40:127-140. [PMID: 31165949 PMCID: PMC6726668 DOI: 10.1007/s10974-019-09520-2] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 05/31/2019] [Indexed: 02/07/2023]
Abstract
It is widely acknowledged that maintenance of muscle, size, strength and endurance is necessary for quality of life and the role that skeletal muscle microcirculation plays in muscle health is becoming increasingly clear. Here we discuss the role that skeletal muscle microcirculation plays in muscle function and plasticity. Besides the density of the capillary network, also the distribution of capillaries is crucial for adequate muscle oxygenation. While capillaries are important for oxygen delivery, the capillary supply to a fibre is related to fibre size rather than oxidative capacity. This link between fibre size and capillary supply is also reflected by the similar time course of hypertrophy and angiogenesis, and the cross-talk between capillaries and satellite cells. A dense vascular network may in fact be more important for a swift repair of muscle damage than the abundance of satellite cells and a lower capillary density may also attenuate the hypertrophic response. Capillary rarefaction does not only occur during ageing, but also during conditions as chronic heart failure, where endothelial apoptosis has been reported to precede muscle atrophy. It has been suggested that capillary rarefaction precedes sarcopenia. If so, stimulation of angiogenesis by for instance endurance training before a hypertrophic stimulus may enhance the hypertrophic response. The microcirculation may thus well be a little-explored target to improve muscle function and the success of rehabilitation programmes during ageing and chronic diseases.
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Affiliation(s)
- Paul Hendrickse
- Research Centre for Musculoskeletal Science & Sports Medicine, School of Healthcare Science, Manchester Metropolitan University, John Dalton Building; Chester Street, Manchester, M1 5GD, UK.,Lithuanian Sports University, Kaunas, Lithuania
| | - Hans Degens
- Research Centre for Musculoskeletal Science & Sports Medicine, School of Healthcare Science, Manchester Metropolitan University, John Dalton Building; Chester Street, Manchester, M1 5GD, UK. .,Lithuanian Sports University, Kaunas, Lithuania. .,University of Medicine and Pharmacy of Targu Mures, Targu Mures, Romania.
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9
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Larsson L, Degens H, Li M, Salviati L, Lee YI, Thompson W, Kirkland JL, Sandri M. Sarcopenia: Aging-Related Loss of Muscle Mass and Function. Physiol Rev 2019; 99:427-511. [PMID: 30427277 DOI: 10.1152/physrev.00061.2017] [Citation(s) in RCA: 777] [Impact Index Per Article: 155.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Sarcopenia is a loss of muscle mass and function in the elderly that reduces mobility, diminishes quality of life, and can lead to fall-related injuries, which require costly hospitalization and extended rehabilitation. This review focuses on the aging-related structural changes and mechanisms at cellular and subcellular levels underlying changes in the individual motor unit: specifically, the perikaryon of the α-motoneuron, its neuromuscular junction(s), and the muscle fibers that it innervates. Loss of muscle mass with aging, which is largely due to the progressive loss of motoneurons, is associated with reduced muscle fiber number and size. Muscle function progressively declines because motoneuron loss is not adequately compensated by reinnervation of muscle fibers by the remaining motoneurons. At the intracellular level, key factors are qualitative changes in posttranslational modifications of muscle proteins and the loss of coordinated control between contractile, mitochondrial, and sarcoplasmic reticulum protein expression. Quantitative and qualitative changes in skeletal muscle during the process of aging also have been implicated in the pathogenesis of acquired and hereditary neuromuscular disorders. In experimental models, specific intervention strategies have shown encouraging results on limiting deterioration of motor unit structure and function under conditions of impaired innervation. Translated to the clinic, if these or similar interventions, by saving muscle and improving mobility, could help alleviate sarcopenia in the elderly, there would be both great humanitarian benefits and large cost savings for health care systems.
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Affiliation(s)
- Lars Larsson
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Hans Degens
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Meishan Li
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Leonardo Salviati
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Young Il Lee
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Wesley Thompson
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - James L Kirkland
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Marco Sandri
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
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Cardinale DA, Larsen FJ, Jensen-Urstad M, Rullman E, Søndergaard H, Morales-Alamo D, Ekblom B, Calbet JAL, Boushel R. Muscle mass and inspired oxygen influence oxygen extraction at maximal exercise: Role of mitochondrial oxygen affinity. Acta Physiol (Oxf) 2019; 225:e13110. [PMID: 29863764 DOI: 10.1111/apha.13110] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 01/12/2023]
Abstract
AIM We examined the Fick components together with mitochondrial O2 affinity (p50mito ) in defining O2 extraction and O2 uptake during exercise with large and small muscle mass during normoxia (NORM) and hyperoxia (HYPER). METHODS Seven individuals performed 2 incremental exercise tests to exhaustion on a bicycle ergometer (BIKE) and 2 on a 1-legged knee extension ergometer (KE) in NORM or HYPER. Leg blood flow and VO2 were determined by thermodilution and the Fick method. Maximal ADP-stimulated mitochondrial respiration (OXPHOS) and p50mito were measured ex vivo in isolated mitochondria. Mitochondrial excess capacity in the leg was determined from OXPHOS in permeabilized fibres and muscle mass measured with magnetic resonance imaging in relation to peak leg O2 delivery. RESULTS The ex vivo p50mito increased from 0.06 ± 0.02 to 0.17 ± 0.04 kPa with varying substrate supply and O2 flux rates from 9.84 ± 2.91 to 16.34 ± 4.07 pmol O2 ·s-1 ·μg-1 respectively. O2 extraction decreased from 83% in BIKE to 67% in KE as a function of a higher O2 delivery and lower mitochondrial excess capacity. There was a significant relationship between O2 extraction and mitochondrial excess capacity and p50mito that was unrelated to blood flow and mean transit time. CONCLUSION O2 extraction varies with mitochondrial respiration rate, p50mito and O2 delivery. Mitochondrial excess capacity maintains a low p50mito which enhances O2 diffusion from microvessels to mitochondria during exercise.
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Affiliation(s)
- D. A. Cardinale
- Åstrand Laboratory of Work Physiology; The Swedish School of Sport and Health Sciences; Stockholm Sweden
- Elite Performance Centre; Bosön, Swedish Sports Confederation; Lidingö Sweden
| | - F. J. Larsen
- Åstrand Laboratory of Work Physiology; The Swedish School of Sport and Health Sciences; Stockholm Sweden
| | - M. Jensen-Urstad
- Department of Cardiology; Karolinska Institute; Karolinska University Hospital; Stockholm Sweden
| | - E. Rullman
- Department of Cardiology; Karolinska Institute; Karolinska University Hospital; Stockholm Sweden
- Department of Laboratory Medicine; Clinical Physiology; Karolinska Institutet; Huddinge Sweden
| | - H. Søndergaard
- The Copenhagen Muscle Research Centre; Rigshospitalet; Copenhagen N Denmark
| | - D. Morales-Alamo
- Department of Physical Education; University of Las Palmas de Gran Canaria; Las Palmas de Gran Canaria Spain
- Research Institute of Biomedical and Health Sciences (IUIBS); Las Palmas de Gran Canaria Spain
| | - B. Ekblom
- Åstrand Laboratory of Work Physiology; The Swedish School of Sport and Health Sciences; Stockholm Sweden
| | - J. A. L. Calbet
- Department of Physical Education; University of Las Palmas de Gran Canaria; Las Palmas de Gran Canaria Spain
- Research Institute of Biomedical and Health Sciences (IUIBS); Las Palmas de Gran Canaria Spain
| | - R. Boushel
- Åstrand Laboratory of Work Physiology; The Swedish School of Sport and Health Sciences; Stockholm Sweden
- School of Kinesiology; University of British Columbia; Vancouver BC Canada
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11
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Time course of denervation-induced changes in gastrocnemius muscles of adult and old rats. Exp Gerontol 2018; 106:165-172. [DOI: 10.1016/j.exger.2018.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 01/31/2018] [Accepted: 03/07/2018] [Indexed: 12/22/2022]
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12
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Barnouin Y, McPhee JS, Butler‐Browne G, Bosutti A, De Vito G, Jones DA, Narici M, Behin A, Hogrel J, Degens H. Coupling between skeletal muscle fiber size and capillarization is maintained during healthy aging. J Cachexia Sarcopenia Muscle 2017; 8:647-659. [PMID: 28382740 PMCID: PMC5566646 DOI: 10.1002/jcsm.12194] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 01/16/2017] [Accepted: 01/26/2017] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND As muscle capillarization is related to the oxidative capacity of the muscle and the size of muscle fibres, capillary rarefaction may contribute to sarcopenia and functional impairment in older adults. Therefore, it is important to assess how ageing affects muscle capillarization and the interrelationship between fibre capillary supply with the oxidative capacity and size of the fibres. METHODS Muscle biopsies from healthy recreationally active young (22 years; 14 men and 5 women) and older (74 years; 22 men and 6 women) people were assessed for muscle capillarization and the distribution of capillaries with the method of capillary domains. Oxidative capacity of muscle fibres was assessed with quantitative histochemistry for succinate dehydrogenase (SDH) activity. RESULTS There was no significant age-related reduction in muscle fibre oxidative capacity. Despite 18% type II fibre atrophy (P = 0.019) and 23% fewer capillaries per fibre (P < 0.002) in the old people, there was no significant difference in capillary distribution between young and old people, irrespective of sex. The capillary supply to a fibre was primarily determined by fibre size and only to a small extent by oxidative capacity, irrespective of age and sex. Based on SDH, the maximal oxygen consumption supported by a capillary did not differ significantly between young and old people. CONCLUSIONS The similar quantitative and qualitative distribution of capillaries within muscle from healthy recreationally active older people and young adults indicates that the age-related capillary rarefaction, which does occur, nevertheless maintains the coupling between skeletal muscle fibre size and capillarization during healthy ageing.
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Affiliation(s)
- Yoann Barnouin
- School of Healthcare ScienceManchester Metropolitan UniversityChester StreetManchesterM1 5GDUK
| | - Jamie S. McPhee
- School of Healthcare ScienceManchester Metropolitan UniversityChester StreetManchesterM1 5GDUK
| | - Gillian Butler‐Browne
- Institut de Myologie, UPMC UM 76, INSERM U 974, CNRS UMR 7215Pitle‐Salpetriere Hospital47‐83 Boulevard de l'Hopital 75013ParisFrance
| | - Alessandra Bosutti
- School of Healthcare ScienceManchester Metropolitan UniversityChester StreetManchesterM1 5GDUK
- Istituto di Anatomia Patologica, Dipartimento di Scienze Mediche, Chirurgiche e della SaluteUniversity of Trieste, Cattinara HospitalStrada di Fiume 44734149TriesteItaly
| | - Giuseppe De Vito
- Physiotherapy & Sports Science, Health Sciences CentreSchool of Public HealthBelfieldDublin 4D04 V1W8Ireland
| | - David A. Jones
- School of Healthcare ScienceManchester Metropolitan UniversityChester StreetManchesterM1 5GDUK
| | - Marco Narici
- Division of Medical Sciences & Graduate Entry Medicine, School of Medicine, Faculty of Medicine & Health Sciences, MRC‐ARUK Centre of Excellence for Musculoskeletal Ageing Research, Derby Royal HospitalUniversity of NottinghamUttoxeter RoadDerbyDE22 3DTUK
| | - Anthony Behin
- AP‐HP—Centre de Référence de Pathologies Neuromusculaire Paris Est—Institut de MyologieParisFrance
| | - Jean‐Yves Hogrel
- Institut de Myologie, UPMC UM 76, INSERM U 974, CNRS UMR 7215Pitle‐Salpetriere Hospital47‐83 Boulevard de l'Hopital 75013ParisFrance
| | - Hans Degens
- School of Healthcare ScienceManchester Metropolitan UniversityChester StreetManchesterM1 5GDUK
- Lithuanian Sports University6 Sporto StLT‐44221KaunasLithuania
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13
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C. Arciero J, Causin P, Malgaroli F. Mathematical methods for modeling the microcirculation. AIMS BIOPHYSICS 2017. [DOI: 10.3934/biophy.2017.3.362] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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14
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Snelling EP, Seymour RS, Green JEF, Meyer LCR, Fuller A, Haw A, Mitchell D, Farrell AP, Costello MA, Izwan A, Badenhorst M, Maloney SK. A structure-function analysis of the left ventricle. J Appl Physiol (1985) 2016; 121:900-909. [PMID: 27586835 DOI: 10.1152/japplphysiol.00435.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 08/25/2016] [Indexed: 11/22/2022] Open
Abstract
This study presents a structure-function analysis of the mammalian left ventricle and examines the performance of the cardiac capillary network, mitochondria, and myofibrils at rest and during simulated heavy exercise. Left ventricular external mechanical work rate was calculated from cardiac output and systemic mean arterial blood pressure in resting sheep (Ovis aries; n = 4) and goats (Capra hircus; n = 4) under mild sedation, followed by perfusion-fixation of the left ventricle and quantification of the cardiac capillary-tissue geometry and cardiomyocyte ultrastructure. The investigation was then extended to heavy exercise by increasing cardiac work according to published hemodynamics of sheep and goats performing sustained treadmill exercise. Left ventricular work rate averaged 0.017 W/cm3 of tissue at rest and was estimated to increase to ∼0.060 W/cm3 during heavy exercise. According to an oxygen transport model we applied to the left ventricular tissue, we predicted that oxygen consumption increases from 195 nmol O2·s-1·cm-3 of tissue at rest to ∼600 nmol O2·s-1·cm-3 during heavy exercise, which is within 90% of the oxygen demand rate and consistent with work remaining predominantly aerobic. Mitochondria represent 21-22% of cardiomyocyte volume and consume oxygen at a rate of 1,150 nmol O2·s-1·cm-3 of mitochondria at rest and ∼3,600 nmol O2·s-1·cm-3 during heavy exercise, which is within 80% of maximum in vitro rates and consistent with mitochondria operating near their functional limits. Myofibrils represent 65-66% of cardiomyocyte volume, and according to a Laplacian model of the left ventricular chamber, generate peak fiber tensions in the range of 50 to 70 kPa at rest and during heavy exercise, which is less than maximum tension of isolated cardiac tissue (120-140 kPa) and is explained by an apparent reserve capacity for tension development built into the left ventricle.
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Affiliation(s)
- Edward P Snelling
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa;
| | - Roger S Seymour
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - J E F Green
- School of Mathematical Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Leith C R Meyer
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa; Department of Paraclinical Sciences, University of Pretoria, Pretoria, South Africa
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa; Department of Paraclinical Sciences, University of Pretoria, Pretoria, South Africa
| | - Anna Haw
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa; School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
| | - Anthony P Farrell
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada; Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mary-Ann Costello
- Central Animal Service, University of the Witwatersrand, Johannesburg, South Africa; and
| | - Adian Izwan
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
| | - Margaret Badenhorst
- School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
| | - Shane K Maloney
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa; School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, Western Australia, Australia
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16
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Wüst RCI, Jaspers RT, van Heijst AF, Hopman MTE, Hoofd LJC, van der Laarse WJ, Degens H. Region-specific adaptations in determinants of rat skeletal muscle oxygenation to chronic hypoxia. Am J Physiol Heart Circ Physiol 2009; 297:H364-74. [PMID: 19429822 DOI: 10.1152/ajpheart.00272.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic exposure to hypoxia is associated with muscle atrophy (i.e., a reduction in muscle fiber cross-sectional area), reduced oxidative capacity, and capillary growth. It is controversial whether these changes are muscle and fiber type specific. We hypothesized that different regions of the same muscle would also respond differently to chronic hypoxia. To investigate this, we compared the deep (oxidative) and superficial (glycolytic) region of the plantaris muscle of eight male rats exposed to 4 wk of hypobaric hypoxia (410 mmHg, Po(2): 11.5 kPa) with those of nine normoxic rats. Hematocrit was higher in chronic hypoxic than control rats (59% vs. 50%, P < 0.001). Using histochemistry, we observed 10% fiber atrophy (P < 0.05) in both regions of the muscle but no shift in the fiber type composition and myoglobin concentration of the fibers. In hypoxic rats, succinate dehydrogenase (SDH) activity was elevated in fibers of each type in the superficial region (25%, P < 0.05) but not in the deep region, whereas in the deep region but not the superficial region the number of capillaries supplying a fiber was elevated (14%, P < 0.05). Model calculations showed that the region-specific alterations in fiber size, SDH activity, and capillary supply to a fiber prevented the occurrence of anoxic areas in the deep region but not in the superficial region. Inclusion of reported acclimatization-induced increases in mean capillary oxygen pressure attenuated the development of anoxic tissue areas in the superficial region of the muscle. We conclude that the determinants of tissue oxygenation show region-specific adaptations, resulting in a marked differential effect on tissue Po(2).
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Affiliation(s)
- R C I Wüst
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, UK.
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Abstract
To improve understanding of microvascular O(2) transport, theoretical modeling has been pursued for many years. The large number of studies in this area attests to the complexities (i.e., biochemical, structural, and hemodynamic) involved. This article focuses on theoretical studies from the last two decades and, in particular, on models of O(2) transport to tissue by discrete microvessels. A brief discussion of intravascular O(2) transport is first given, highlighting the physiological importance of intravascular resistance to blood-tissue O(2) transfer. This is followed by a description of the Krogh tissue cylinder model of O(2) transport by a single capillary, which is shown to remain relevant in modified forms that relax many of the original biophysical assumptions. However, there are many geometric and hemodynamic complexities that require the consideration of microvascular arrays and networks. Multivessel models are discussed that have shown the physiological importance of heterogeneities in vessel spacing, O(2) supply, red blood cell flow path, as well as interactions between capillaries and arterioles. These realistic models require sophisticated methods for solving the governing partial differential equations, and a range of solution techniques are described. Finally, the issue of experimental validation of microvascular O(2) delivery models is discussed, and new directions in O(2) transport modeling are outlined.
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Affiliation(s)
- Daniel Goldman
- Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada.
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18
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Degens H, Morse CI, Hopman MTE. Heterogeneity of capillary spacing in the hypertrophied plantaris muscle from young-adult and old rats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 645:61-6. [PMID: 19227451 DOI: 10.1007/978-0-387-85998-9_10] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Heterogeneity of capillary spacing may affect tissue oxygenation. The determinants of heterogeneity of capillary spacing are, however, unknown. To investigate whether 1) impaired angiogenesis and increased heterogeneity of capillary spacing delays development of hypertrophy during aging and 2) heterogeneity of capillary spacing is determined by variations in fiber size we overloaded the left m. plantaris in young-adult (5-month-old) and old (25-month-old) rats for 1, 2 or 4 weeks by denervation of synergists, while the right leg served as an internal control. Fiber size, capillary density and capillary to fiber ratio were similar in control young-adult and old muscles. The time course and degree of hypertrophy were similar at both ages, indicating that in rats up to the age of 25 months the hypertrophic response is maintained. The variation in fiber size and heterogeneity of capillary spacing were, however, larger in old than young-adult muscles, larger in the superficial than the deep region of the muscle, and correlated significantly (R = 0.558; P < 0.001). This suggests that part of the heterogeneity of capillary spacing is due to heterogeneity in fiber size and may reflect that morphological constraints for positioning of capillaries partly determines heterogeneity of capillary spacing in muscle.
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Affiliation(s)
- Hans Degens
- Instititute for biophysical and Clinical Research into Human Movement, Manchester Metropolitan University, Alsager, ST7 2HL, UK.
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Goldman D, Bateman RM, Ellis CG. Effect of decreased O2 supply on skeletal muscle oxygenation and O2 consumption during sepsis: role of heterogeneous capillary spacing and blood flow. Am J Physiol Heart Circ Physiol 2006; 290:H2277-85. [PMID: 16399873 DOI: 10.1152/ajpheart.00547.2005] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
One of the main aspects of the initial phase of the septic inflammatory response to a bacterial infection is abnormal microvascular perfusion, including decreased functional capillary density (FCD) and increased blood flow heterogeneity. On the other hand, one of the most important phenomena observed in the later stages of sepsis is an increased dependence of tissue O(2) utilization on the convective O(2) supply. This "pathological supply dependency" is associated with organ failure and poor clinical outcomes. Here, a detailed theoretical model of capillary-to-tissue O(2) transport during sepsis is used to examine the origins of abnormal supply dependency. With use of three-dimensional arrays of capillaries with heterogeneous spacing and blood flow, steady-state O(2) transport is simulated numerically during reductions in the O(2) supply. Increased supply dependency is shown to occur in sepsis for hypoxic (decreased hemoglobin O(2) saturation) and stagnant (decreased blood flow) hypoxia. For stagnant hypoxia, a reduction in FCD with decreasing blood flow is necessary to obtain the observed increase in supply dependency. Our results imply that supply dependency observed under normal conditions does not have its origin at the level of individual capillaries. In sepsis, however, diffusion limitation and shunting of O(2) by individual capillaries occur to a degree that is dependent on the heterogeneity of septic injury and the arrangement of capillary networks. Thus heterogeneous stoppage of individual capillaries is a likely factor in pathological supply dependency.
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Affiliation(s)
- Daniel Goldman
- Department of Mathematical Sciences, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, USA.
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Skovgaard N, Galli G, Abe A, Taylor EW, Wang T. The role of nitric oxide in regulation of the cardiovascular system in reptiles. Comp Biochem Physiol A Mol Integr Physiol 2005; 142:205-14. [PMID: 15982914 DOI: 10.1016/j.cbpb.2005.05.049] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 05/20/2005] [Accepted: 05/21/2005] [Indexed: 11/19/2022]
Abstract
The roles that nitric oxide (NO) plays in the cardiovascular system of reptiles are reviewed, with particular emphasis on its effects on central vascular blood flows in the systemic and pulmonary circulations. New data is presented that describes the effects on hemodynamic variables in varanid lizards of exogenously administered NO via the nitric oxide donor sodium nitroprusside (SNP) and inhibition of nitric oxide synthase (NOS) by l-nitroarginine methyl ester (l-NAME). Furthermore, preliminary data on the effects of SNP on hemodynamic variables in the tegu lizard are presented. The findings are compared with previously published data from our laboratory on three other species of reptiles: pythons (), rattlesnakes () and turtles (). These five species of reptiles possess different combinations of division of the heart and structural complexity of the lungs. Comparison of their responses to NO donors and NOS inhibitors may reveal whether the potential contribution of NO to vascular tone correlates with pulmonary complexity and/or with blood pressure. All existing studies on reptiles have clearly established a potential role for NO in regulating vascular tone in the systemic circulation and NO may be important for maintaining basal systemic vascular tone in varanid lizards, pythons and turtles, through a continuous release of NO. In contrast, the pulmonary circulation is less responsive to NO donors or NOS inhibitors, and it was only in pythons and varanid lizards that the lungs responded to SNP. Both species have a functionally separated heart, so it is possible that NO may exert a larger role in species with low pulmonary blood pressures, irrespective of lung complexity.
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Affiliation(s)
- Nini Skovgaard
- Departamento de Zoologia, Centro de Aguicultura, UNESP, Caixa Postal 199, 13506-907 Rio Claro, Brazil.
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Robergs RA, Icenogle MV, Hudson TL, Greene ER. Temporal inhomogeneity in brachial artery blood flow during forearm exercise. Med Sci Sports Exerc 1997; 29:1021-7. [PMID: 9268958 DOI: 10.1097/00005768-199708000-00006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The purpose of this study was to measure the influences of muscle contraction and exercise intensity on brachial artery blood flow during incremental forearm wrist flexion exercise to fatigue. Twelve subjects performed incremental forearm exercise (increments of 0.1 W every 5 min) with their nondominant arms. Doppler waveforms and two-dimensional images of the brachial artery were recorded during the last 2 min of each stage. Exercise intensities were expressed as a percent of the maximal workload achieved (%WLmax). Blood flow was calculated during each of the concentric (CP), eccentric (EP), and recovery phases (RP) of the contraction cycle. Blood flow during the CP of the contraction did not increase above resting values (25.0 +/- 10.5 mL.min-1) at any intensity (100%WLmax = 21.6 +/- 6.5 mL.min-1). Conversely, blood flow during the EP and RP increased from 25.6 +/- 3.0 to 169.1 +/- 12.8 (P < 0.05), and from 24.7 +/- 3.1 to 137.9 +/- 19.5 mL.min-1 (P < 0.05), respectively from rest to maximal exercise. Time averaged blood flow increased linearly from rest to maximal exercise (75.3 +/- 26.3 to 334.6 +/- 141.6 mL.min-1, P < 0.05). Thus, a significant impairment in blood flow occurs with concentric contractions during forearm dynamic exercise. The implications of a temporal disparity in blood flow to oxygen delivery and skeletal metabolism during exercise are discussed.
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Affiliation(s)
- R A Robergs
- Center for Exercise and Applied Human Physiology, University of New Mexico, Albuquerque, USA.
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Piiper J. Oxygen supply to exercising muscle: roles of diffusion limitation and heterogeneity of blood flow. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1994; 361:503-7. [PMID: 7597976 DOI: 10.1007/978-1-4615-1875-4_89] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- J Piiper
- Max-Planck-Institut für experimentelle Medizin, Göttingen, Germany
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Piiper J. Oxygen supply by perfusion and diffusion in heterogeneous tissue models. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1992; 317:623-7. [PMID: 1288180 DOI: 10.1007/978-1-4615-3428-0_73] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- J Piiper
- Abteilung Physiologie, Max-Planck-Institut für experimentelle Medizin, Göttingen, Germany
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