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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] [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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Theodorakopoulou MP, Zafeiridis A, Dipla K, Faitatzidou D, Koutlas A, Alexandrou ME, Doumas M, Papagianni A, Sarafidis P. Muscle Oxygenation and Microvascular Reactivity Across Different Stages of CKD: A Near-Infrared Spectroscopy Study. Am J Kidney Dis 2023; 81:655-664.e1. [PMID: 36608922 DOI: 10.1053/j.ajkd.2022.11.013] [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: 08/25/2022] [Accepted: 11/19/2022] [Indexed: 01/05/2023]
Abstract
RATIONALE & OBJECTIVE Previous studies in chronic kidney disease (CKD) showed that vascular dysfunction in different circulatory beds progressively deteriorates with worsening CKD severity. This study evaluated muscle oxygenation and microvascular reactivity at rest, during an occlusion-reperfusion maneuver, and during exercise in patients with different stages of CKD versus controls. STUDY DESIGN Observational controlled study. SETTING & PARTICIPANTS 90 participants (18 per CKD stage 2, 3a, 3b, and 4, as well as 18 controls). PREDICTOR CKD stage. OUTCOME The primary outcome was muscle oxygenation at rest. Secondary outcomes were muscle oxygenation during occlusion-reperfusion and exercise, and muscle microvascular reactivity (hyperemic response). ANALYTICAL APPROACH Continuous measurement of muscle oxygenation [tissue saturation index (TSI)] using near-infrared spectroscopy at rest, during occlusion-reperfusion, and during a 3-minute handgrip exercise (at 35% of maximal voluntary contraction). Aortic pulse wave velocity and carotid intima-media thickness were also recorded. RESULTS Resting muscle oxygenation did not differ across the study groups (controls: 64.3% ± 2.9%; CKD stage 2: 63.8% ± 4.2%; CKD stage 3a: 64.1% ± 4.1%; CKD stage 3b: 62.3% ± 3.3%; CKD stage 4: 62.7% ± 4.3%; P=0.6). During occlusion, no significant differences among groups were detected in the TSI occlusion magnitude and TSI occlusion slope. However, during reperfusion the maximum TSI value was significantly lower in groups of patients with more advanced CKD stages compared with controls, as was the hyperemic response (controls: 11.2%±3.7%; CKD stage 2: 8.3%±4.6%; CKD stage 3: 7.8%±5.5%; CKD stage 3b: 7.3%±4.4%; CKD stage 4: 7.2%±3.3%; P=0.04). During the handgrip exercise, the average decline in TSI was marginally lower in patients with CKD than controls, but no significant differences were detected across CKD stages. LIMITATIONS Moderate sample size, cross-sectional evaluation. CONCLUSIONS Although no differences were observed in muscle oxygenation at rest or during occlusion, the microvascular hyperemic response during reperfusion was significantly impaired in CKD and was most prominent in more advanced CKD stages. This impaired ability of microvasculature to respond to stimuli may be a crucial component of the adverse vascular profile of patients with CKD and may contribute to exercise intolerance.
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Affiliation(s)
- Marieta P Theodorakopoulou
- Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Andreas Zafeiridis
- Exercise Physiology & Biochemistry Laboratory, Department of Sport Sciences at Serres, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Konstantina Dipla
- Exercise Physiology & Biochemistry Laboratory, Department of Sport Sciences at Serres, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Danai Faitatzidou
- Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Angelos Koutlas
- Exercise Physiology & Biochemistry Laboratory, Department of Sport Sciences at Serres, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Maria-Eleni Alexandrou
- Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Michael Doumas
- Second Propedeutic Department of Internal Medicine, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Aikaterini Papagianni
- Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Pantelis Sarafidis
- Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.
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Nyberg M, Jones AM. Matching of O2 Utilization and O2 Delivery in Contracting Skeletal Muscle in Health, Aging, and Heart Failure. Front Physiol 2022; 13:898395. [PMID: 35774284 PMCID: PMC9237395 DOI: 10.3389/fphys.2022.898395] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 05/05/2022] [Indexed: 12/12/2022] Open
Abstract
Skeletal muscle is one of the most dynamic metabolic organs as evidenced by increases in metabolic rate of >150-fold from rest to maximal contractile activity. Because of limited intracellular stores of ATP, activation of metabolic pathways is required to maintain the necessary rates of ATP re-synthesis during sustained contractions. During the very early phase, phosphocreatine hydrolysis and anaerobic glycolysis prevails but as activity extends beyond ∼1 min, oxidative phosphorylation becomes the major ATP-generating pathway. Oxidative metabolism of macronutrients is highly dependent on the cardiovascular system to deliver O2 to the contracting muscle fibres, which is ensured through a tight coupling between skeletal muscle O2 utilization and O2 delivery. However, to what extent O2 delivery is ideal in terms of enabling optimal metabolic and contractile function is context-dependent and determined by a complex interaction of several regulatory systems. The first part of the review focuses on local and systemic mechanisms involved in the regulation of O2 delivery and how integration of these influences the matching of skeletal muscle O2 demand and O2 delivery. In the second part, alterations in cardiovascular function and structure associated with aging and heart failure, and how these impact metabolic and contractile function, will be addressed. Where applicable, the potential of exercise training to offset/reverse age- and disease-related cardiovascular declines will be highlighted in the context of skeletal muscle metabolic function. The review focuses on human data but also covers animal observations.
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Affiliation(s)
- Michael Nyberg
- Vascular Biology, Global Drug Discovery, Novo Nordisk A/S, Maaloev, Denmark
- *Correspondence: Michael Nyberg,
| | - Andrew M. Jones
- Department of Sport and Health Sciences, University of Exeter, Exeter, United Kingdom
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4
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Taylor E, Hill RP, Létourneau D. Modeling the impact of spatial oxygen heterogeneity on radiolytic oxygen depletion during FLASH radiotherapy. Phys Med Biol 2022; 67. [PMID: 35576920 DOI: 10.1088/1361-6560/ac702c] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 05/16/2022] [Indexed: 12/12/2022]
Abstract
Purpose.It has been postulated that the delivery of radiotherapy at ultra-high dose rates ('FLASH') reduces normal tissue toxicities by depleting them of oxygen. The fraction of normal tissue and cancer cells surviving radiotherapy depends on dose and oxygen levels in an exponential manner and even a very small fraction of tissue at low oxygen levels can determine radiotherapy response. To quantify the differential impact of FLASH radiotherapy on normal and tumour tissues, the spatial heterogeneity of oxygenation in tissue should thus be accounted for.Methods.The effect of FLASH on radiation-induced normal and tumour tissue cell killing was studied by simulating oxygen diffusion, metabolism, and radiolytic oxygen depletion (ROD) over domains with simulated capillary architectures. To study the impact of heterogeneity, two architectural models were used: (1) randomly distributed capillaries and (2) capillaries forming a regular square lattice array. The resulting oxygen partial pressure distribution histograms were used to simulate normal and tumour tissue cell survival using the linear quadratic model of cell survival, modified to incorporate oxygen-enhancement ratio effects. The ratio ('dose modifying factors') of conventional low-dose-rate dose and FLASH dose at iso-cell survival was computed and compared with empirical iso-toxicity dose ratios.Results.Tumour cell survival was found to be increased by FLASH as compared to conventional radiotherapy, with a 0-1 order of magnitude increase for expected levels of tumour hypoxia, depending on the relative magnitudes of ROD and tissue oxygen metabolism. Interestingly, for the random capillary model, the impact of FLASH on well-oxygenated (normal) tissues was found to be much greater, with an estimated increase in cell survival by up to 10 orders of magnitude, even though reductions in mean tissue partial pressure were modest, less than ∼7 mmHg for the parameter values studied. The dose modifying factor for normal tissues was found to lie in the range 1.2-1.7 for a representative value of normal tissue oxygen metabolic rate, consistent with preclinical iso-toxicity results.Conclusions.The presence of very small nearly hypoxic regions in otherwise well-perfused normal tissues with high mean oxygen levels resulted in a greater proportional sparing of normal tissue than tumour cells during FLASH irradiation, possibly explaining empirical normal tissue sparing and iso-tumour control results.
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Affiliation(s)
- Edward Taylor
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
| | - Richard P Hill
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Daniel Létourneau
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
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Horrell HD, Lindeque A, Farrell AP, Seymour RS, White CR, Kruger KM, Snelling EP. Relationship between capillaries, mitochondria and maximum power of the heart: a meta-study from shrew to elephant. Proc Biol Sci 2022; 289:20212461. [PMID: 35135343 PMCID: PMC8825986 DOI: 10.1098/rspb.2021.2461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This meta-study uses phylogenetic scaling models across more than 30 species, spanning five orders of magnitude in body mass, to show that cardiac capillary numerical density and mitochondrial volume density decrease with body mass raised to the -0.07 ± 0.03 and -0.04 ± 0.01 exponents, respectively. Thus, while an average 10 g mammal has a cardiac capillary density of approximately 4150 mm-2 and a mitochondrial density of 33%, a 1 t mammal has considerably lower corresponding values of 1850 mm-2 and 21%. These similar scaling trajectories suggest quantitative matching for the primary oxygen supply and oxygen consuming structures of the heart, supporting economic design at the cellular level of the oxygen cascade in this aerobic organ. These scaling trajectories are nonetheless somewhat shallower than the exponent of -0.11 calculated for the maximum external mechanical power of the cardiac tissue, under conditions of heavy exercise, when oxygen flow between capillaries and mitochondria is probably fully exploited. This mismatch, if substantiated, implies a declining external mechanical efficiency of the heart with increasing body mass, whereby larger individuals put more energy in but get less energy out, a scenario with implications for cardiovascular design, aerobic capacity and limits of body size.
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Affiliation(s)
- Heidi D. Horrell
- Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa,Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Anika Lindeque
- Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - 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
| | - Roger S. Seymour
- School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Craig R. White
- Centre for Geometric Biology, School of Biological Sciences, Faculty of Science, Monash University, Clayton, Victoria, Australia
| | - Kayla M. Kruger
- Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Edward P. Snelling
- Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa,Centre for Veterinary Wildlife Research, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
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The importance of capillary distribution in supporting muscle function, building on Krogh's seminal ideas. Comp Biochem Physiol A Mol Integr Physiol 2021; 254:110889. [DOI: 10.1016/j.cbpa.2020.110889] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/21/2020] [Accepted: 12/21/2020] [Indexed: 12/11/2022]
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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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8
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Gan GCH, Bhat A, Chen HHL, Gu KH, Fernandez F, Kadappu KK, Byth K, Eshoo S, Thomas L. Left Atrial Reservoir Strain by Speckle Tracking Echocardiography: Association With Exercise Capacity in Chronic Kidney Disease. J Am Heart Assoc 2020; 10:e017840. [PMID: 33372523 PMCID: PMC7955492 DOI: 10.1161/jaha.120.017840] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Background Left atrial (LA) function plays a pivotal role in modulating left ventricular performance. The aim of our study was to evaluate the relationship between resting LA function by strain analysis and exercise capacity in patients with chronic kidney disease (CKD) and evaluate its utility compared with exercise E/e'. Methods and Results Consecutive patients with stage 3 and 4 CKD without prior cardiac history were prospectively recruited from outpatient nephrology clinics and underwent clinical evaluation and resting and exercise stress echocardiography. Resting echocardiographic parameters including E/e' and phasic LA strain (LA reservoir [LASr], conduit, and contractile strain) were measured and compared with exercise E/e'. A total of 218 (63.9±11.7 years, 64% men) patients with CKD were recruited. Independent clinical parameters associated with exercise capacity were age, estimated glomerular filtration rate, body mass index, and sex (P<0.01 for all), while independent resting echocardiographic parameters included E/e', LASr, and LA contractile strain (P<0.01 for all). Among resting echocardiographic parameters, LASr demonstrated the strongest positive correlation to metabolic equivalents achieved (r=0.70; P<0.01). Receiver operating characteristic curves demonstrated that LASr (area under the curve, 0.83) had similar diagnostic performance as exercise E/e' (area under the curve, 0.79; P=0.20 on DeLong test). A model combining LASr and clinical metrics showed robust association with metabolic equivalents achieved in patients with CKD. Conclusions LASr, a marker of decreased LA compliance is an independent correlate of exercise capacity in patients with stage 3 and 4 CKD, with similar diagnostic value to exercise E/e'. Thus, LASr may serve as a resting biomarker of functional capacity in this population.
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Affiliation(s)
- Gary C H Gan
- Department of Cardiology Blacktown Hospital Sydney NSW Australia.,Department of Cardiology Westmead Hospital Sydney NSW Australia.,University of New South Wales Sydney NSW Australia.,Western Sydney University Sydney NSW Australia
| | - Aditya Bhat
- Department of Cardiology Blacktown Hospital Sydney NSW Australia.,University of New South Wales Sydney NSW Australia.,Western Sydney University Sydney NSW Australia
| | - Henry H L Chen
- Department of Cardiology Blacktown Hospital Sydney NSW Australia
| | - Kennith H Gu
- Department of Cardiology Blacktown Hospital Sydney NSW Australia.,Western Sydney University Sydney NSW Australia
| | | | - Krishna K Kadappu
- University of New South Wales Sydney NSW Australia.,Western Sydney University Sydney NSW Australia.,Department of Cardiology Liverpool Hospital Sydney NSW Australia.,Department of Cardiology Campbelltown Hospital Sydney NSW Australia
| | - Karen Byth
- Research and Education Network Western Sydney Local Health District Sydney NSW Australia
| | - Suzanne Eshoo
- Department of Cardiology Blacktown Hospital Sydney NSW Australia.,Western Sydney University Sydney NSW Australia
| | - Liza Thomas
- Department of Cardiology Westmead Hospital Sydney NSW Australia.,University of New South Wales Sydney NSW Australia.,University of Sydney Sydney NSW Australia
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9
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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] [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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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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11
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Egginton S, Kissane RWP, Al-Shammari AA, Gaffney EA. Quantifying fiber type-specific local capillary supply. J Appl Physiol (1985) 2020; 128:458-459. [PMID: 32073333 DOI: 10.1152/japplphysiol.00853.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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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12
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Aubert V, Kaminski J, Guillaud F, Hauet T, Hannaert P. A Computer Model of Oxygen Dynamics in the Cortex of the Rat Kidney at the Cell-Tissue Level. Int J Mol Sci 2019; 20:E6246. [PMID: 31835730 PMCID: PMC6941061 DOI: 10.3390/ijms20246246] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 12/02/2019] [Accepted: 12/05/2019] [Indexed: 02/06/2023] Open
Abstract
The renal cortex drives renal function. Hypoxia/reoxygenation are primary factors in ischemia-reperfusion (IR) injuries, but renal oxygenation per se is complex and awaits full elucidation. Few mathematical models address this issue: none captures cortical tissue heterogeneity. Using agent-based modeling, we develop the first model of cortical oxygenation at the cell-tissue level (RCM), based on first principles and careful bibliographical analysis. Entirely parameterized with Rat data, RCM is a morphometrically equivalent 2D-slice of cortical tissue, featuring peritubular capillaries (PTC), tubules and interstitium. It implements hemoglobin/O2 binding-release, oxygen diffusion, and consumption, as well as capillary and tubular flows. Inputs are renal blood flow RBF and PO2 feeds; output is average tissue PO2 (tPO2). After verification and sensitivity analysis, RCM was validated at steady-state (tPO2 37.7 ± 2.2 vs. 36.9 ± 6 mmHg) and under transients (ischemic oxygen half-time: 4.5 ± 2.5 vs. 2.3 ± 0.5 s in situ). Simulations confirm that PO2 is largely independent of RBF, except at low values. They suggest that, at least in the proximal tubule, the luminal flow dominantly contributes to oxygen delivery, while the contribution of capillaries increases under partial ischemia. Before addressing IR-induced injuries, upcoming developments include ATP production, adaptation to minutes-hours scale, and segmental and regional specification.
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Affiliation(s)
| | | | | | | | - Patrick Hannaert
- INSERM U1082-IRTOMIT, 86000 Poitiers, France; (V.A.); (J.K.); (F.G.); (T.H.)
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Astaxanthin: A Potential Mitochondrial-Targeted Antioxidant Treatment in Diseases and with Aging. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:3849692. [PMID: 31814873 PMCID: PMC6878783 DOI: 10.1155/2019/3849692] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 08/30/2019] [Indexed: 12/23/2022]
Abstract
Oxidative stress is characterized by an imbalance between prooxidant and antioxidant species, leading to macromolecular damage and disruption of redox signaling and cellular control. It is a hallmark of various diseases including metabolic syndrome, chronic fatigue syndrome, neurodegenerative, cardiovascular, inflammatory, and age-related diseases. Several mitochondrial defects have been considered to contribute to the development of oxidative stress and known as the major mediators of the aging process and subsequent age-associated diseases. Thus, mitochondrial-targeted antioxidants should prevent or slow down these processes and prolong longevity. This is the reason why antioxidant treatments are extensively studied and newer and newer compounds with such an effect appear. Astaxanthin, a xanthophyll carotenoid, is the most abundant carotenoid in marine organisms and is one of the most powerful natural compounds with remarkable antioxidant activity. Here, we summarize its antioxidant targets, effects, and benefits in diseases and with aging.
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Changes in local capillarity of pure and hybrid MyHC muscle fiber types after nerve injury in rat extensor digitorum longus muscle (EDL). Histochem Cell Biol 2019; 152:89-107. [DOI: 10.1007/s00418-019-01787-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2019] [Indexed: 10/26/2022]
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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: 710] [Impact Index Per Article: 142.0] [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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Effects of treadmill training on microvascular remodeling in the rat after spinal cord injury. Muscle Nerve 2018; 59:370-379. [DOI: 10.1002/mus.26379] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 10/29/2018] [Accepted: 11/03/2018] [Indexed: 01/06/2023]
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18
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Restricted exchange microenvironments for cell culture. Biotechniques 2018; 64:101-109. [PMID: 29570441 DOI: 10.2144/btn-2017-0110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 02/07/2018] [Indexed: 11/23/2022] Open
Abstract
Metabolite diffusion in tissues produces gradients and heterogeneous microenvironments that are not captured in standard 2D cell culture models. Here we describe restricted exchange environment chambers (REECs) in which diffusive gradients are formed and manipulated on length scales approximating those found in vivo. In REECs, cells are grown in 2D in an asymmetric chamber (<50 μL) formed between a coverglass and a glass bottom cell culture dish separated by a thin (~100 μm) gasket. Diffusive metabolite exchange between the chamber and bulk media occurs through one or more openings micromachined into the coverglass. Cell-generated concentration gradients form radially in REECs with a single round opening (~200 μm diameter). At steady state only cells within several hundred micrometers of the opening experience metabolite concentrations that permit survival which is analogous to diffusive exchange near a capillary in tissue. The chamber dimensions, the openings' shape, size, and number, and the cellular density and metabolic activity define the gradient structure. For example, two parallel slots above confluent cells produce the 1D equivalent of a spheroid. Using REECs, we found that fibroblasts align along the axis of diffusion while MDCK cells do not. MDCK cells do, however, exhibit significant morphological variations along the diffusive gradient.
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Snelling EP, Maloney SK, Farrell AP, Meyer LCR, Izwan A, Fuller A, Mitchell D, Haw A, Costello MA, Seymour RS. Scaling of morphology and ultrastructure of hearts among wild African antelope. J Exp Biol 2018; 221:jeb.184713. [DOI: 10.1242/jeb.184713] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 06/29/2018] [Indexed: 11/20/2022]
Abstract
The hearts of smaller mammals tend to operate at higher mass-specific mechanical work rates than those of larger mammals. The ultrastructural characteristics of the heart that allow for such variation in work rate still is largely unknown. We have used perfusion-fixation, transmission electron microscopy and stereology to assess the morphology and anatomical aerobic power density of the heart as a function of body mass across six species of wild African antelope differing by approximately 20-fold in body mass. The survival of wild antelope, as prey animals, depends on competent cardiovascular performance. We found that relative heart mass (g kg−1 body mass) decreases with body mass according to a power equation with an exponent of –0.12±0.07 (± 95% CI) (P=0.0027). Likewise, capillary length density (km cm−3 of cardiomyocyte), mitochondrial volume density (fraction of cardiomyocyte), and mitochondrial inner membrane surface density (m2 cm−3 of mitochondria) also decrease with body mass with exponents of –0.17±0.16 (P=0.039), –0.06±0.05 (P=0.018), and –0.07±0.05 (P=0.015), respectively, trends likely to be associated with the greater mass-specific mechanical work rates of the hearts in smaller antelope. Finally, we found proportionality between quantitative characteristics of a structure responsible for the delivery of oxygen (total capillary length) and those of a structure that ultimately uses that oxygen (total mitochondrial inner membrane surface area), which provides support for the economic principle of symmorphosis at the cellular level of the oxygen cascade in an aerobic organ.
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Affiliation(s)
- Edward P. Snelling
- Brain Function Research Group, 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 Human Sciences, 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
| | - 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
| | - Adian Izwan
- School of Human Sciences, University of Western Australia, Crawley, Western Australia, Australia
| | - 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
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
- School of Human Sciences, University of Western Australia, Crawley, Western Australia, Australia
| | - Anna Haw
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
| | - Mary-Ann Costello
- Central Animal Service, University of the Witwatersrand, Johannesburg, South Africa
| | - Roger S. Seymour
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
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Eržen I, Janáček J, Kreft M, Kubínová L, Cvetko E. Capillary Network Morphometry of Pig Soleus Muscle Significantly Changes in 24 Hours After Death. J Histochem Cytochem 2018; 66:23-31. [PMID: 29095670 PMCID: PMC5761944 DOI: 10.1369/0022155417737061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/20/2017] [Indexed: 11/22/2022] Open
Abstract
Capillary network characteristics are invaluable for diagnostics of muscle diseases. Biopsy material is limited in size and mostly not accessible for intensive research. Therefore, especially in human tissue, studies are performed on autopsy material. To approach the problem whether it is reliable to deduce hypotheses from autopsy material to explain physiological and pathological processes, we studied capillarity in pig soleus muscle 1 and 24 hr after death. Capillaries and muscle fibers were immunofluorescently marked, and images were acquired with a confocal microscope. Characteristics of the capillary network were estimated by image analysis methods using several plugins of the Ellipse program. Twenty-four hours after death, the measured characteristics of the capillary network differ by up to 50% when compared with samples excised 1 hr after death. Muscle fiber diameter, the measured capillary length, and tortuosity were reduced, and capillary network became more anisotropic. The main postmortem change that affects capillaries is evidently geometric deformation of muscle tissue. In conclusion, when comparing results from biopsy samples with those from autopsy samples, the effect of postmortem changes on the measured parameters must be carefully considered.
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Affiliation(s)
- Ida Eržen
- Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Jiří Janáček
- Department of Biomathematics, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Marko Kreft
- Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Celica Biomedical, Ljubljana, Slovenia
| | - Lucie Kubínová
- Department of Biomathematics, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Erika Cvetko
- Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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21
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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: 61] [Impact Index Per Article: 8.7] [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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Harter TS, Brauner CJ. The O 2 and CO 2 Transport System in Teleosts and the Specialized Mechanisms That Enhance Hb–O 2 Unloading to Tissues. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/bs.fp.2017.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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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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Tabola R, Augoff K, Lewandowski A, Ziolkowski P, Szelachowski P, Grabowski K. Esophageal anastomosis - how the granulation phase of wound healing improves the incidence of anastomotic leakage. Oncol Lett 2016; 12:2038-2044. [PMID: 27602135 DOI: 10.3892/ol.2016.4873] [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: 01/31/2016] [Accepted: 06/02/2016] [Indexed: 12/22/2022] Open
Abstract
A two-stage esophagectomy with an interval for reconstruction of the esophagus creates an opportunity for the esophageal stump to recover from vessel injury and allows the formation of granulation tissue rich in proangiogenic factors, including transforming growth factor β (TGF-β) and vascular endothelial growth factor A (VEGF-A), which may have an impact on anastomosis healing. The present study comprised 25 patients (27 in total, 2 succumbed to complications following surgery) who underwent two-stage esophagectomy for squamous cell carcinoma in the Department of Gastrointestinal and General Surgery, Wrocław Medical University (Wrocław, Poland) between January 2007 and December 2012. Immunohistochemical staining for VEGF-A and TGF-β was performed to evaluate esophageal wall specimens at the time of esophagostomy construction and prior to anastomosis, in which the cervical esophagus was connected with the colon or ileum. At the time of reconstructive surgery, a significant increase in microvessel density was observed in all esophageal specimens (P<0.03). Significant differences were also identified in the immunohistochemical staining intensity of TGF-β and VEGF-A in the epithelium of all esophageal specimens between biopsies obtained from normal esophageal tissues at the time of esophagectomy and during reconstructive surgery. Delayed anastomosis construction provides an advantage for the esophageal stump to accumulate proangiogenic growth factors, which overlap with the subsequent proliferative stage of the anastomosed tissue and thus supports its recovery, creating an optimal environment for the healing of any fistulas.
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Affiliation(s)
- Renata Tabola
- Department of Gastrointestinal and General Surgery, Wrocław Medical University, 50-369 Wrocław, Poland
| | - Katarzyna Augoff
- Department of Gastrointestinal and General Surgery, Wrocław Medical University, 50-369 Wrocław, Poland
| | - Andrzej Lewandowski
- Department of Gastrointestinal and General Surgery, Wrocław Medical University, 50-369 Wrocław, Poland
| | - Piotr Ziolkowski
- Department of Pathomorphology, Wrocław Medical University, 50-369 Wrocław, Poland
| | - Piotr Szelachowski
- Department of Gastrointestinal and General Surgery, Wrocław Medical University, 50-369 Wrocław, Poland
| | - Krzysztof Grabowski
- Department of Gastrointestinal and General Surgery, Wrocław Medical University, 50-369 Wrocław, Poland
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Abstract
Aerobic exercise training leads to cardiovascular changes that markedly increase aerobic power and lead to improved endurance performance. The functionally most important adaptation is the improvement in maximal cardiac output which is the result of an enlargement in cardiac dimension, improved contractility, and an increase in blood volume, allowing for greater filling of the ventricles and a consequent larger stroke volume. In parallel with the greater maximal cardiac output, the perfusion capacity of the muscle is increased, permitting for greater oxygen delivery. To accommodate the higher aerobic demands and perfusion levels, arteries, arterioles, and capillaries adapt in structure and number. The diameters of the larger conduit and resistance arteries are increased minimizing resistance to flow as the cardiac output is distributed in the body and the wall thickness of the conduit and resistance arteries is reduced, a factor contributing to increased arterial compliance. Endurance training may also induce alterations in the vasodilator capacity, although such adaptations are more pronounced in individuals with reduced vascular function. The microvascular net increases in size within the muscle allowing for an improved capacity for oxygen extraction by the muscle through a greater area for diffusion, a shorter diffusion distance, and a longer mean transit time for the erythrocyte to pass through the smallest blood vessels. The present article addresses the effect of endurance training on systemic and peripheral cardiovascular adaptations with a focus on humans, but also covers animal data.
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Affiliation(s)
- Ylva Hellsten
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Michael Nyberg
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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26
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Haas TL, Nwadozi E. Regulation of skeletal muscle capillary growth in exercise and disease. Appl Physiol Nutr Metab 2015; 40:1221-32. [PMID: 26554747 DOI: 10.1139/apnm-2015-0336] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Capillaries, which are the smallest and most abundant type of blood vessel, form the primary site of gas, nutrient, and waste transfer between the vascular and tissue compartments. Skeletal muscle exhibits the capacity to generate new capillaries (angiogenesis) as an adaptation to exercise training, thus ensuring that the heightened metabolic demand of the active muscle is matched by an improved capacity for distribution of gases, nutrients, and waste products. This review summarizes the current understanding of the regulation of skeletal muscle capillary growth. The multi-step process of angiogenesis is coordinated through the integration of a diverse array of signals associated with hypoxic, metabolic, hemodynamic, and mechanical stresses within the active muscle. The contributions of metabolic and mechanical factors to the modulation of key pro- and anti-angiogenic molecules are discussed within the context of responses to a single aerobic exercise bout and short-term and long-term training. Finally, the paradoxical lack of angiogenesis in peripheral artery disease and diabetes and the implications for disease progression and muscle health are discussed. Future studies that emphasize an integrated analysis of the mechanisms that control skeletal muscle capillary growth will enable development of targeted exercise programs that effectively promote angiogenesis in healthy individuals and in patient populations.
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Affiliation(s)
- Tara L Haas
- Angiogenesis Research Group, York University, Toronto, ON M3J 1P3, Canada.,Angiogenesis Research Group, York University, Toronto, ON M3J 1P3, Canada
| | - Emmanuel Nwadozi
- Angiogenesis Research Group, York University, Toronto, ON M3J 1P3, Canada.,Angiogenesis Research Group, York University, Toronto, ON M3J 1P3, Canada
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27
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Hoying JB, Utzinger U, Weiss JA. Formation of microvascular networks: role of stromal interactions directing angiogenic growth. Microcirculation 2015; 21:278-89. [PMID: 24447042 PMCID: PMC4032604 DOI: 10.1111/micc.12115] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Accepted: 01/16/2014] [Indexed: 12/29/2022]
Abstract
In the adult, angiogenesis leads to an expanded microvascular network as new vessel segments are added to an existing microcirculation. Necessarily, growing neovessels must navigate through tissue stroma as they locate and grow toward other vessel elements. We have a growing body of evidence demonstrating that angiogenic neovessels reciprocally interact with the interstitial matrix of the stroma resulting in directed neovascular growth during angiogenesis. Given the compliance and the viscoelastic properties of collagen, neovessel guidance by the stroma is likely due to compressive strain transverse to the direction of primary tensile forces present during active tissue deformation. Similar stromal strains control the final network topology of the new microcirculation, including the distribution of arterioles, capillaries, and venules. In this case, stromal-derived stimuli must be present during the post-angiogenesis remodeling and maturation phases of neovascularization to have this effect. Interestingly, the preexisting organization of vessels prior to the start of angiogenesis has no lasting influence on the final, new network architecture. Combined, the evidence describes interplay between angiogenic neovessels and stroma that is important in directed neovessel growth and invasion. This dynamic is also likely a mechanism by which global tissue forces influence vascular form and function.
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Affiliation(s)
- James B Hoying
- Cardiovascular Innovation Institute, University of Louisville, Louisville, Kentucky, USA
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28
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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] [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] [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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30
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Javan H, Szucsik AM, Li L, Schaaf CL, Salama ME, Selzman CH. Cardiomyocyte p65 nuclear factor-κB is necessary for compensatory adaptation to pressure overload. Circ Heart Fail 2014; 8:109-18. [PMID: 25480781 DOI: 10.1161/circheartfailure.114.001297] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND Nuclear factor κB (NF-κB) is often implicated in contributing to the detrimental effects of cardiac injury. This ostensibly negative view of NF-κB competes with its important role in the normal host inflammatory and immune response. We have previously demonstrated that pharmacological inhibition of NF-κB at the time of acute pressure overload accelerates the progression of left ventricular hypertrophy to heart failure in mice. NF-κB regulates angiogenesis and other factors responsible for compensatory reaction to intracellular hypoxia. We hypothesized that impaired angiogenesis may be the trigger, not the result, of pathological left ventricular hypertrophy through NF-κB-related pathways. METHODS AND RESULTS Transgenic mice were generated with cardiomyocyte-specific deletion of the p65 subunit of NF-κB. Mice underwent transverse aortic constriction and serially followed up with echocardiography for 6 weeks. Cardiomyocyte p65 NF-κB deletion promoted maladaptive left ventricular hypertrophy and accelerated progression toward heart failure as measured by ejection fraction, left ventricular mass, and lung congestion. Transgenic mice had higher levels of fibrosis and periostin expression. Whole-field digital microscopy revealed increased capillary domain areas in knockout mice while concurrently demonstrating decreased microvessel density. This observation was associated with decreased expression of hypoxia-inducible factor 1α. CONCLUSIONS Rather than developing compensatory left ventricular hypertrophy, pressure overload in cardiomyocyte NF-κB-deficient mice resulted in functional deterioration that was associated with increased fibrosis, decreased hypoxia-inducible factor expression, and decreased microvessel density. These observations mechanistically implicate NF-κB, and its regulation of hypoxic stress, as an important factor determining the path between adaptive hypertrophy and maladaptive heart failure.
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Affiliation(s)
- Hadi Javan
- From the Division of Cardiothoracic Surgery, Department of Surgery and Molecular Medicine (H.J., A.M.S., L.L., C.L.S., C.H.S.) and Department of Pathology, ARUP Institute for Research and Development (M.E.S.), University of Utah, Salt Lake City
| | - Amanda M Szucsik
- From the Division of Cardiothoracic Surgery, Department of Surgery and Molecular Medicine (H.J., A.M.S., L.L., C.L.S., C.H.S.) and Department of Pathology, ARUP Institute for Research and Development (M.E.S.), University of Utah, Salt Lake City
| | - Ling Li
- From the Division of Cardiothoracic Surgery, Department of Surgery and Molecular Medicine (H.J., A.M.S., L.L., C.L.S., C.H.S.) and Department of Pathology, ARUP Institute for Research and Development (M.E.S.), University of Utah, Salt Lake City
| | - Christin L Schaaf
- From the Division of Cardiothoracic Surgery, Department of Surgery and Molecular Medicine (H.J., A.M.S., L.L., C.L.S., C.H.S.) and Department of Pathology, ARUP Institute for Research and Development (M.E.S.), University of Utah, Salt Lake City
| | - Mohamed E Salama
- From the Division of Cardiothoracic Surgery, Department of Surgery and Molecular Medicine (H.J., A.M.S., L.L., C.L.S., C.H.S.) and Department of Pathology, ARUP Institute for Research and Development (M.E.S.), University of Utah, Salt Lake City
| | - Craig H Selzman
- From the Division of Cardiothoracic Surgery, Department of Surgery and Molecular Medicine (H.J., A.M.S., L.L., C.L.S., C.H.S.) and Department of Pathology, ARUP Institute for Research and Development (M.E.S.), University of Utah, Salt Lake City.
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31
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Al-Shammari AA, Gaffney EA, Egginton S. Modelling capillary oxygen supply capacity in mixed muscles: Capillary domains revisited. J Theor Biol 2014; 356:47-61. [DOI: 10.1016/j.jtbi.2014.04.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Revised: 04/11/2014] [Accepted: 04/15/2014] [Indexed: 12/24/2022]
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32
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Leirós GJ, Kusinsky AG, Drago H, Bossi S, Sturla F, Castellanos ML, Stella IY, Balañá ME. Dermal papilla cells improve the wound healing process and generate hair bud-like structures in grafted skin substitutes using hair follicle stem cells. Stem Cells Transl Med 2014; 3:1209-19. [PMID: 25161315 DOI: 10.5966/sctm.2013-0217] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Tissue-engineered skin represents a useful strategy for the treatment of deep skin injuries and might contribute to the understanding of skin regeneration. The use of dermal papilla cells (DPCs) as a dermal component in a permanent composite skin with human hair follicle stem cells (HFSCs) was evaluated by studying the tissue-engineered skin architecture, stem cell persistence, hair regeneration, and graft-take in nude mice. A porcine acellular dermal matrix was seeded with HFSCs alone and with HFSCs plus human DPCs or dermal fibroblasts (DFs). In vitro, the presence of DPCs induced a more regular and multilayered stratified epidermis with more basal p63-positive cells and invaginations. The DPC-containing constructs more accurately mimicked the skin architecture by properly stratifying the differentiating HFSCs and developing a well-ordered epithelia that contributed to more closely recapitulate an artificial human skin. This acellular dermal matrix previously repopulated in vitro with HFSCs and DFs or DPCs as the dermal component was grafted in nude mice. The presence of DPCs in the composite substitute not only favored early neovascularization, good assimilation and remodeling after grafting but also contributed to the neovascular network maturation, which might reduce the inflammation process, resulting in a better healing process, with less scarring and wound contraction. Interestingly, only DPC-containing constructs showed embryonic hair bud-like structures with cells of human origin, presence of precursor epithelial cells, and expression of a hair differentiation marker. Although preliminary, these findings have demonstrated the importance of the presence of DPCs for proper skin repair.
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Affiliation(s)
- Gustavo José Leirós
- Fundación Pablo Cassará, Instituto de Ciencia y Tecnología Dr. César Milstein, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina; Banco de Tejidos, Hospital de Quemados de la Ciudad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina; Centro de Estudios Biomédicos, Ambientales y Diagnóstico, Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina
| | - Ana Gabriela Kusinsky
- Fundación Pablo Cassará, Instituto de Ciencia y Tecnología Dr. César Milstein, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina; Banco de Tejidos, Hospital de Quemados de la Ciudad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina; Centro de Estudios Biomédicos, Ambientales y Diagnóstico, Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina
| | - Hugo Drago
- Fundación Pablo Cassará, Instituto de Ciencia y Tecnología Dr. César Milstein, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina; Banco de Tejidos, Hospital de Quemados de la Ciudad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina; Centro de Estudios Biomédicos, Ambientales y Diagnóstico, Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina
| | - Silvia Bossi
- Fundación Pablo Cassará, Instituto de Ciencia y Tecnología Dr. César Milstein, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina; Banco de Tejidos, Hospital de Quemados de la Ciudad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina; Centro de Estudios Biomédicos, Ambientales y Diagnóstico, Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina
| | - Flavio Sturla
- Fundación Pablo Cassará, Instituto de Ciencia y Tecnología Dr. César Milstein, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina; Banco de Tejidos, Hospital de Quemados de la Ciudad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina; Centro de Estudios Biomédicos, Ambientales y Diagnóstico, Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina
| | - María Lía Castellanos
- Fundación Pablo Cassará, Instituto de Ciencia y Tecnología Dr. César Milstein, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina; Banco de Tejidos, Hospital de Quemados de la Ciudad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina; Centro de Estudios Biomédicos, Ambientales y Diagnóstico, Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina
| | - Inés Yolanda Stella
- Fundación Pablo Cassará, Instituto de Ciencia y Tecnología Dr. César Milstein, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina; Banco de Tejidos, Hospital de Quemados de la Ciudad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina; Centro de Estudios Biomédicos, Ambientales y Diagnóstico, Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina
| | - María Eugenia Balañá
- Fundación Pablo Cassará, Instituto de Ciencia y Tecnología Dr. César Milstein, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina; Banco de Tejidos, Hospital de Quemados de la Ciudad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina; Centro de Estudios Biomédicos, Ambientales y Diagnóstico, Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina
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Green HJ, Ranney D, Burnett M, Galvin P, Kyle N, Iqbal S, Lounsbury D, Ouyang J, Smith IC, Stewart R, Tick H, Tupling AR. A pilot study to determine whether differences exist in histochemical properties between the trapezius and extensor carpi radialis brevis muscles in women with work-related myalgia. Can J Physiol Pharmacol 2014; 92:315-23. [PMID: 24708214 DOI: 10.1139/cjpp-2013-0301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To investigate fibre-type abnormalities in women with work-related myalgia (WRM), tissue samples were extracted from their trapezius (TRAP) and the extensor carpi radialis brevis (ECRB) muscles and compared with healthy controls (CON). For the ECRB samples (CON, n = 6; WRM, n = 11), no differences (P > 0.05) were found between groups for any of the properties examined, namely fibre-type (I, IIA, IIX, IIAX) distribution, cross-sectional fibre area, capillary counts (CC), capillary to fibre area ratio, and succinic dehydrogenase activity. For the TRAP samples (CON, n = 6; WRM, n = 8), the only difference (P < 0.05) observed between groups was for CC (CON > WRM), which was not statistically significant (P > 0.05) when age was used a covariant. A comparison of the properties of these 2 muscles in the CON group indicated a higher (P < 0.05) and lower (P < 0.05) percentage of type I and type IIA fibres, respectively, in the TRAP as well as higher (P < 0.05) CC, which was not specific to fibre type. These preliminary results suggest that the properties employed to characterize fibre types do not differentiate CON from WRM for either the TRAP or ECRB. As a consequence, the role of inherent fibre-type differences between these muscles in the pathogenesis of WRM remains uncertain.
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Affiliation(s)
- Howard J. Green
- Department of Kinesiology and the Centre of Research Expertise for the Prevention of Musculoskeletal Disorders (CRE-MSD), University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Don Ranney
- Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
- Disability Assessment Services, Inc., Waterloo, Ontario, Canada
| | - Margaret Burnett
- Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Patti Galvin
- Wellington Orthopaedic and Rehabilitation Clinic Centre, 86 Dawson Street, Unit 3, Guelph, Ontario, Canada
| | - Natasha Kyle
- Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Sobia Iqbal
- Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - David Lounsbury
- Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Jing Ouyang
- Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Ian C. Smith
- Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Riley Stewart
- Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Heather Tick
- Mind Body Medicine, The RSI Clinic, Toronto, Ontario, Canada
- Department of Anaesthesiology and Pain Medicine, University of Washington, Seattle, USA
| | - A. Russell Tupling
- Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
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LeBlanc AJ, Krishnan L, Sullivan CJ, Williams SK, Hoying JB. Microvascular repair: post-angiogenesis vascular dynamics. Microcirculation 2013; 19:676-95. [PMID: 22734666 DOI: 10.1111/j.1549-8719.2012.00207.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Vascular compromise and the accompanying perfusion deficits cause or complicate a large array of disease conditions and treatment failures. This has prompted the exploration of therapeutic strategies to repair or regenerate vasculatures, thereby establishing more competent microcirculatory beds. Growing evidence indicates that an increase in vessel numbers within a tissue does not necessarily promote an increase in tissue perfusion. Effective regeneration of a microcirculation entails the integration of new stable microvessel segments into the network via neovascularization. Beginning with angiogenesis, neovascularization entails an integrated series of vascular activities leading to the formation of a new mature microcirculation, and includes vascular guidance and inosculation, vessel maturation, pruning, AV specification, network patterning, structural adaptation, intussusception, and microvascular stabilization. While the generation of new vessel segments is necessary to expand a network, without the concomitant neovessel remodeling and adaptation processes intrinsic to microvascular network formation, these additional vessel segments give rise to a dysfunctional microcirculation. While many of the mechanisms regulating angiogenesis have been detailed, a thorough understanding of the mechanisms driving post-angiogenesis activities specific to neovascularization has yet to be fully realized, but is necessary to develop effective therapeutic strategies for repairing compromised microcirculations as a means to treat disease.
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Affiliation(s)
- Amanda J LeBlanc
- Cardiovascular Innovation Institute, Jewish Hospital and St. Mary's Healthcare and University of Louisville, Louisville, Kentucky 40202, USA
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Kanazashi M, Okumura Y, Al-Nassan S, Murakami S, Kondo H, Nagatomo F, Fujita N, Ishihara A, Roy RR, Fujino H. Protective effects of astaxanthin on capillary regression in atrophied soleus muscle of rats. Acta Physiol (Oxf) 2013; 207:405-15. [PMID: 23088455 DOI: 10.1111/apha.12018] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 09/11/2012] [Accepted: 09/17/2012] [Indexed: 11/28/2022]
Abstract
AIM The capillary regression in skeletal muscles associated with a chronic decrease in activity is related to a dysfunction of endocapillary cells induced by over-expression of oxidative stress. We hypothesized that treatment with astaxanthin, an antioxidant, would attenuate the oxidative stress induced by decreased skeletal muscle use, and that this attenuation would prevent the associated capillary regression. The purpose of the present study was to investigate the antioxidant and preventive effects of astaxanthin on capillary regression in the soleus muscle during hindlimb unloading. METHODS Twenty-four adult male Wistar rats were assigned randomly either to a control, control plus astaxanthin treatment, hindlimb unloaded or hindlimb unloaded plus astaxanthin treatment group for 7 days. RESULTS Hindlimb unloading resulted in a decrease in mean soleus absolute weight, capillary number, volume and luminal diameter. The accumulation of reactive oxygen species and the over-expression of superoxide dismutase (SOD-1), a decrease in the levels of vascular endothelial growth factor (VEGF) and its receptors, an inhibition of the angiopoietin pathway and an increase of thrombospondin-1 (TSP-1), as an anti-angiogenic factor were showed. Administration of astaxanthin attenuated the changes in SOD-1 and VEGF, up-regulated the angiogenic factors and reduced the capillary regression in the soleus of hindlimb unloaded rats. In addition, the VEGF-to-TSP1 ratio was higher in the astaxanthin treated groups than in the control and HU groups. CONCLUSION These results suggest that astaxanthin may be an effective treatment to counter the detrimental effects of a chronic decrease in skeletal muscle use on the capillary network and associated angiogenic pathways.
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Affiliation(s)
- M. Kanazashi
- Department of Rehabilitation Science; Kobe University Graduate School of Health Sciences; Kobe; Japan
| | - Y. Okumura
- Department of Rehabilitation Science; Kobe University Graduate School of Health Sciences; Kobe; Japan
| | - S. Al-Nassan
- Department of Rehabilitation Science; Kobe University Graduate School of Health Sciences; Kobe; Japan
| | | | - H. Kondo
- Department of Food Sciences and Nutrition; Nagoya Women's University; Nagoya; Japan
| | - F. Nagatomo
- Laboratory of Cell Biology and Life Science; Graduate School of Human and Environmental Studies, Kyoto University; Kyoto; Japan
| | - N. Fujita
- Department of Rehabilitation Science; Kobe University Graduate School of Health Sciences; Kobe; Japan
| | - A. Ishihara
- Laboratory of Cell Biology and Life Science; Graduate School of Human and Environmental Studies, Kyoto University; Kyoto; Japan
| | - R. R. Roy
- Brain Research Institute and Department of Integrative Biology and Physiology; University of California; Los Angeles; CA; USA
| | - H. Fujino
- Department of Rehabilitation Science; Kobe University Graduate School of Health Sciences; Kobe; Japan
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Okumura Y, Kanazashi M, Kanazawa Y, Fujita N, Kondo H, Fujino H. Differential Effects of Astaxanthin on Oxidative Key Enzyme and Capillarization in the Deep and Superficial Layers of Unloading-induced Atrophied Muscle. J Phys Ther Sci 2013. [DOI: 10.1589/jpts.25.349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Yu Okumura
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences:7-10-2 Tomogaoka, Suma-Ku, Kobe 654-0142, Japan
| | - Miho Kanazashi
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences:7-10-2 Tomogaoka, Suma-Ku, Kobe 654-0142, Japan
| | - Yuji Kanazawa
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences:7-10-2 Tomogaoka, Suma-Ku, Kobe 654-0142, Japan
| | - Naoto Fujita
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences:7-10-2 Tomogaoka, Suma-Ku, Kobe 654-0142, Japan
| | - Hiroyo Kondo
- Department of Food Science and Nutrition, Nagoya Woman’s University
| | - Hidemi Fujino
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences:7-10-2 Tomogaoka, Suma-Ku, Kobe 654-0142, Japan
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Abstract
Peripheral arterial disease (PAD) is a common vascular disease that reduces blood flow capacity to the legs of patients. PAD leads to exercise intolerance that can progress in severity to greatly limit mobility, and in advanced cases leads to frank ischemia with pain at rest. It is estimated that 12 to 15 million people in the United States are diagnosed with PAD, with a much larger population that is undiagnosed. The presence of PAD predicts a 50% to 1500% increase in morbidity and mortality, depending on severity. Treatment of patients with PAD is limited to modification of cardiovascular disease risk factors, pharmacological intervention, surgery, and exercise therapy. Extended exercise programs that involve walking approximately five times per week, at a significant intensity that requires frequent rest periods, are most significant. Preclinical studies and virtually all clinical trials demonstrate the benefits of exercise therapy, including improved walking tolerance, modified inflammatory/hemostatic markers, enhanced vasoresponsiveness, adaptations within the limb (angiogenesis, arteriogenesis, and mitochondrial synthesis) that enhance oxygen delivery and metabolic responses, potentially delayed progression of the disease, enhanced quality of life indices, and extended longevity. A synthesis is provided as to how these adaptations can develop in the context of our current state of knowledge and events known to be orchestrated by exercise. The benefits are so compelling that exercise prescription should be an essential option presented to patients with PAD in the absence of contraindications. Obviously, selecting for a lifestyle pattern that includes enhanced physical activity prior to the advance of PAD limitations is the most desirable and beneficial.
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Affiliation(s)
- Tara L Haas
- Angiogenesis Research Group, Muscle Health Research Centre, Faculty of Health, York University, Toronto, Ontario, Canada
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Re-evaluating the Use of Voronoi Tessellations in the Assessment of Oxygen Supply from Capillaries in Muscle. Bull Math Biol 2012; 74:2204-31. [DOI: 10.1007/s11538-012-9753-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 07/03/2012] [Indexed: 10/28/2022]
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39
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Cadore EL, Izquierdo M, Conceição M, Radaelli R, Pinto RS, Baroni BM, Vaz MA, Alberton CL, Pinto SS, Cunha G, Bottaro M, Kruel LFM. Echo intensity is associated with skeletal muscle power and cardiovascular performance in elderly men. Exp Gerontol 2012; 47:473-8. [DOI: 10.1016/j.exger.2012.04.002] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 04/02/2012] [Accepted: 04/06/2012] [Indexed: 12/27/2022]
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40
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Mechanisms of vessel regression: toward an understanding of the resolution of angiogenesis. Curr Top Microbiol Immunol 2012; 367:3-32. [PMID: 23224648 DOI: 10.1007/82_2012_287] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Physiological angiogenesis refers to a naturally occurring process of blood vessel growth and regression, and it occurs as an integral component of tissue repair and regeneration. During wound healing, sprouting and branching results in an extensive yet immature and leaky neovascular network that ultimately resolves by systematic pruning of extraneous vessels to yield a stable, well-perfused vascular network ideally suited to maintain tissue homeostasis. While the molecular mechanisms of blood vessel growth have been explored in numerous cell and animal models in remarkable detail, the endogenous factors that prevent further angiogenesis and control vessel regression have not received much attention and are largely unknown. In this review, we introduce the relevant literature from various disciplines to fill the gaps in the current limited understanding of the major molecular and biomechanical inducers of vascular regression. The processes are described in the context of endothelial cell biology during wound healing: hypoxia-driven activation and sprouting followed by apoptosis or maturation of cells comprising the vasculature. We discuss and integrate the likely roles of a variety of endogenous factors, including oxygen availability, vessel perfusion and shear stress, intracellular negative feedback mechanisms (Spry2, vasohibin), soluble cytokines (CXCL10), matrix-binding proteins (TSP, PEDF), protein cleavage products (angiostatin, vasostatin), matrix-derived anti-angiogenic peptides (endostatin, arresten, canstatin, tumstatin), and the biomechanical properties of remodeling the extra-cellular matrix itself. These factors aid in the spatio-temporal control of blood vessel pruning by inducing specific anti-angiogenic signaling pathways in activated endothelial cells, pathways which compete with pro-angiogenic and maturation signals in the resolving wound. Gaining more insight into these mechanisms is bound to shed light on unresolved questions regarding scar formation, tissue regeneration, and increase our understanding of the many diseases with angiogenic phenotypes, especially cancer.
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Abstract
(1) Angiogenesis (growth of new capillaries from an existing capillary bed) may result from a mismatch in microvascular supply and metabolic demand (metabolic error signal). Krogh examined the distribution and number of capillaries to explore the correlation between O(2) delivery and O(2) consumption. Subsequently, the heterogeneity in angiogenic response within a muscle has been shown to reflect either differences in fibre type composition or mechanical load. However, local control leads to targetted angiogenesis in the vicinity of glycolytic fibre types following muscle stimulation, or oxidative fibres following endurance training, while heterogeneity of capillary spacing is maintained during ontogenetic growth. (2) Despite limited microscopy resolution and lack of specific markers, Krogh's interest in the structure of the capillary wall paved the way for understanding the mechanisms of capillary growth. Angiogenesis may be influenced by the response of perivascular or stromal cells (fibroblasts, macrophages and pericytes) to altered activity, likely acting as a source for chemical signals modulating capillary growth such as vascular endothelial growth factor. In addition, haemodynamic factors such as shear stress and muscle stretch play a significant role in adaptive remodelling of the microcirculation. (3) Most indices of capillarity are highly dependent on fibre size, resulting in possible bias because of scaling. To examine the consequences of capillary distribution, it is therefore helpful to quantify the area of tissue supplied by individual capillaries. This allows the spatial limitations inherent in most models of tissue oxygenation to be overcome generating an alternative approach to Krogh's tissue cylinder, the capillary domain, to improve descriptions of intracellular oxygen diffusion.
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Affiliation(s)
- S Egginton
- Department of Physiology, University of Birmingham, Birmingham, UK.
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Venditti P, Napolitano G, Di Stefano L, Agnisola C, Di Meo S. Effect of vitamin E administration on response to ischaemia-reperfusion of hearts from cold-exposed rats. Exp Physiol 2011; 96:635-46. [DOI: 10.1113/expphysiol.2011.058289] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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