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Elsaid NMH, Peters DC, Galiana G, Sinusas AJ. Clinical physiology: the crucial role of MRI in evaluation of peripheral artery disease. Am J Physiol Heart Circ Physiol 2024; 326:H1304-H1323. [PMID: 38517227 DOI: 10.1152/ajpheart.00533.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 03/19/2024] [Accepted: 03/19/2024] [Indexed: 03/23/2024]
Abstract
Peripheral artery disease (PAD) is a common vascular disease that primarily affects the lower limbs and is defined by the constriction or blockage of peripheral arteries and may involve microvascular dysfunction and tissue injury. Patients with diabetes have more prominent disease of microcirculation and develop peripheral neuropathy, autonomic dysfunction, and medial vascular calcification. Early and accurate diagnosis of PAD and disease characterization are essential for personalized management and therapy planning. Magnetic resonance imaging (MRI) provides excellent soft tissue contrast and multiplanar imaging capabilities and is useful as a noninvasive imaging tool in the comprehensive physiological assessment of PAD. This review provides an overview of the current state of the art of MRI in the evaluation and characterization of PAD, including an analysis of the many applicable MR imaging techniques, describing the advantages and disadvantages of each approach. We also present recent developments, future clinical applications, and future MRI directions in assessing PAD. The development of new MR imaging technologies and applications in preclinical models with translation to clinical research holds considerable potential for improving the understanding of the pathophysiology of PAD and clinical applications for improving diagnostic precision, risk stratification, and treatment outcomes in patients with PAD.
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Affiliation(s)
- Nahla M H Elsaid
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Dana C Peters
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, United States
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, United States
| | - Gigi Galiana
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, United States
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, United States
| | - Albert J Sinusas
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, United States
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, United States
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, United States
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Michel CP, Messonnier LA, Giannesini B, Chatel B, Vilmen C, Le Fur Y, Bendahan D. Effects of Hydroxyurea on Skeletal Muscle Energetics and Function in a Mildly Anemic Mouse Model. Front Physiol 2022; 13:915640. [PMID: 35784862 PMCID: PMC9240423 DOI: 10.3389/fphys.2022.915640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
Hydroxyurea (HU) is a ribonucleotide reductase inhibitor most commonly used as a therapeutic agent in sickle cell disease (SCD) with the aim of reducing the risk of vaso-occlusion and improving oxygen transport to tissues. Previous studies suggest that HU may be even beneficial in mild anemia. However, the corresponding effects on skeletal muscle energetics and function have never been reported in such a mild anemia model. Seventeen mildly anemic HbAA Townes mice were subjected to a standardized rest-stimulation (transcutaneous stimulation)-protocol while muscle energetics using 31Phosphorus magnetic resonance spectroscopy and muscle force production were assessed and recorded. Eight mice were supplemented with hydroxyurea (HU) for 6 weeks while 9 were not (CON). HU mice displayed a higher specific total force production compared to the CON, with 501.35 ± 54.12 N/mm3 and 437.43 ± 57.10 N/mm3 respectively (+14.6%, p < 0.05). Neither the total rate of energy consumption nor the oxidative metabolic rate were significantly different between groups. The present results illustrated a positive effect of a HU chronic supplementation on skeletal muscle function in mice with mild anemia.
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Affiliation(s)
- Constance P. Michel
- CRMBM, CNRS, Aix Marseille University, Marseille, France
- *Correspondence: Constance P. Michel,
| | - Laurent A. Messonnier
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, Chambéry, France
| | | | - Benjamin Chatel
- CRMBM, CNRS, Aix Marseille University, Marseille, France
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, Chambéry, France
| | | | - Yann Le Fur
- CRMBM, CNRS, Aix Marseille University, Marseille, France
| | - David Bendahan
- CRMBM, CNRS, Aix Marseille University, Marseille, France
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Lewis MT, Kasper JD, Bazil JN, Frisbee JC, Wiseman RW. Quantification of Mitochondrial Oxidative Phosphorylation in Metabolic Disease: Application to Type 2 Diabetes. Int J Mol Sci 2019; 20:E5271. [PMID: 31652915 PMCID: PMC6862501 DOI: 10.3390/ijms20215271] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/17/2019] [Accepted: 10/22/2019] [Indexed: 12/17/2022] Open
Abstract
Type 2 diabetes (T2D) is a growing health concern with nearly 400 million affected worldwide as of 2014. T2D presents with hyperglycemia and insulin resistance resulting in increased risk for blindness, renal failure, nerve damage, and premature death. Skeletal muscle is a major site for insulin resistance and is responsible for up to 80% of glucose uptake during euglycemic hyperglycemic clamps. Glucose uptake in skeletal muscle is driven by mitochondrial oxidative phosphorylation and for this reason mitochondrial dysfunction has been implicated in T2D. In this review we integrate mitochondrial function with physiologic function to present a broader understanding of mitochondrial functional status in T2D utilizing studies from both human and rodent models. Quantification of mitochondrial function is explained both in vitro and in vivo highlighting the use of proper controls and the complications imposed by obesity and sedentary lifestyle. This review suggests that skeletal muscle mitochondria are not necessarily dysfunctional but limited oxygen supply to working muscle creates this misperception. Finally, we propose changes in experimental design to address this question unequivocally. If mitochondrial function is not impaired it suggests that therapeutic interventions and drug development must move away from the organelle and toward the cardiovascular system.
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Affiliation(s)
- Matthew T Lewis
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA.
| | - Jonathan D Kasper
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA.
- Present address: Molecular Physiology Institute, Duke University, Durham, NC 27701, USA.
| | - Jason N Bazil
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA.
| | - Jefferson C Frisbee
- Department of Medical Biophysics, University of Western Ontario, London, ON N6A 3K7, Canada.
| | - Robert W Wiseman
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA.
- Department of Radiology, Michigan State University, East Lansing, MI 48824, USA.
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Frisbee JC, Lewis MT, Wiseman RW. Skeletal muscle performance in metabolic disease: Microvascular or mitochondrial limitation or both? Microcirculation 2018; 26:e12517. [PMID: 30471168 DOI: 10.1111/micc.12517] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 11/14/2018] [Indexed: 12/20/2022]
Abstract
One of the clearly established health outcomes associated with chronic metabolic diseases (eg, type II diabetes mellitus) is that the ability of skeletal muscle to maintain contractile performance during periods of elevated metabolic demand is compromised as compared to the fatigue-resistance of muscle under normal, healthy conditions. While there has been extensive effort dedicated to determining the major factors that contribute to the compromised performance of skeletal muscle with chronic metabolic disease, the extent to which this poor outcome reflects a dysfunctional state of the microcirculation, where the delivery and distribution of metabolic substrates can be impaired, versus derangements to normal metabolic processes and mitochondrial function, versus a combination of the two, represents an area of considerable unknown. The purpose of this manuscript is to present some of the current concepts for dysfunction to both the microcirculation of skeletal muscle as well as to mitochondrial metabolism under these conditions, such that these diverse issues can be merged into an integrated framework for future investigation. Based on an interpretation of the current literature, it may be hypothesized that the primary site of dysfunction with earlier stages of metabolic disease may lie at the level of the vasculature, rather than at the level of the mitochondria.
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Affiliation(s)
- Jefferson C Frisbee
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Matthew T Lewis
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Robert W Wiseman
- Department of Physiology, Michigan State University, East Lansing, Michigan.,Department of Radiology, Michigan State University, East Lansing, Michigan
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Ripley EM, Clarke GD, Hamidi V, Martinez RA, Settles FD, Solis C, Deng S, Abdul-Ghani M, Tripathy D, DeFronzo RA. Reduced skeletal muscle phosphocreatine concentration in type 2 diabetic patients: a quantitative image-based phosphorus-31 MR spectroscopy study. Am J Physiol Endocrinol Metab 2018; 315:E229-E239. [PMID: 29509433 PMCID: PMC6139498 DOI: 10.1152/ajpendo.00426.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mitochondrial function has been examined in insulin-resistant (IR) states including type 2 diabetes mellitus (T2DM). Previous studies using phosphorus-31 magnetic resonance spectroscopy (31P-MRS) in T2DM reported results as relative concentrations of metabolite ratios, which could obscure differences in phosphocreatine ([PCr]) and adenosine triphosphate concentrations ([ATP]) between T2DM and normal glucose tolerance (NGT) individuals. We used an image-guided 31P-MRS method to quantitate [PCr], inorganic phosphate [Pi], phosphodiester [PDE], and [ATP] in vastus lateralis (VL) muscle in 11 T2DM and 14 NGT subjects. Subjects also received oral glucose tolerance test, euglycemic insulin clamp, 1H-MRS to measure intramyocellular lipids [IMCL], and VL muscle biopsy to evaluate mitochondrial density. T2DM subjects had lower absolute [PCr] and [ATP] than NGT subjects (PCr 28.6 ± 3.2 vs. 24.6 ± 2.4, P < 0.002, and ATP 7.18 ± 0.6 vs. 6.37 ± 1.1, P < 0.02) while [PDE] was higher, but not significantly. [PCr], obtained using the traditional ratio method, showed no significant difference between groups. [PCr] was negatively correlated with HbA1c ( r = -0.63, P < 0.01) and fasting plasma glucose ( r = -0.51, P = 0.01). [PDE] was negatively correlated with Matsuda index ( r = -0.43, P = 0.03) and M/I ( r = -0.46, P = 0.04), but was positively correlated with [IMCL] ( r = 0.64, P < 0.005), HbA1c, and FPG ( r = 0.60, P = 0.001). To summarize, using a modified, in vivo quantitative 31P-MRS method, skeletal muscle [PCr] and [ATP] are reduced in T2DM, while this difference was not observed with the traditional ratio method. The strong inverse correlation between [PCr] vs. HbA1c, FPG, and insulin sensitivity supports the concept that lower baseline skeletal muscle [PCr] is related to key determinants of glucose homeostasis.
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Affiliation(s)
- Erika M Ripley
- Department of Radiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Geoffrey D Clarke
- Department of Radiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
- Research Imaging Institute, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Vala Hamidi
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Robert A Martinez
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Floyd D Settles
- Department of Radiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Carolina Solis
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Shengwen Deng
- Research Imaging Institute, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Muhammad Abdul-Ghani
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Devjit Tripathy
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Ralph A DeFronzo
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
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Šedivý P, Kipfelsberger MC, Dezortová M, Krššák M, Drobný M, Chmelík M, Rydlo J, Trattnig S, Hájek M, Valkovič L. Dynamic 31P MR spectroscopy of plantar flexion: influence of ergometer design, magnetic field strength (3 and 7 T), and RF-coil design. Med Phys 2015; 42:1678-89. [PMID: 25832057 DOI: 10.1118/1.4914448] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Dynamic phosphorus magnetic resonance spectroscopy ((31)P MRS) during and after acute exercise enables the noninvasive in vivo determination of the mitochondrial capacity of skeletal muscle. Nevertheless, the lack of standardization in experimental setups leads to significant variations in published values of maximal aerobic capacity, even in the population of healthy volunteers. Thus, in this study, we aimed to assess the impact of the ergometer type (pneumatic and mechanical resistance construction), radiofrequency (RF)-coil diameter, and different magnetic field strengths (3 and 7 T) on the metabolic parameters measured by dynamic (31)P MRS during a plantar flexion isotonic exercise protocol within the same group of healthy volunteers. METHODS Dynamic (31)P MRS measurements of the calf muscle in 11 volunteers (mean age, 36 ± 13 yrs; mean BMI, 23.5 ± 2.5 kg/m(2)), on a 3 T MR system with a custom-made mechanical ergometer in the first research laboratory (RL1) and on 3 and 7 T MR systems equipped with a commercial pneumatic ergometer in the second research laboratory (RL2), were performed at three different workloads. RF-coils differed slightly between the sites and MR systems used. The repeatability of the experimental protocol was tested in every setup. The basal concentrations of phosphocreatine (PCr), exercise-induced depletion of PCr (ΔPCr), initial PCr resynthesis rate (VPCr), and mitochondrial capacity (Qmax) were calculated and compared between the research sites and field strengths. RESULTS High repeatability of the measurement protocol was found in every experimental setup. No significant differences at any workload were found in these metabolic parameters assessed at different magnetic field strengths (3 T vs 7 T), using the same ergometer (in RL2) and a similar RF-coil. In the inter-research laboratory comparison at the same field strength (3 T), but with using different ergometers and RF-coils, differences were found in the concentration of PCr measured at rest and in the drop in PCr signal intensity. These differences translated into difference in the value of mitochondrial capacity at a workload of 15% of maximal voluntary contraction (MVC) force (0.45 ± 0.16 mM/s vs 0.31 ± 0.08 mM/s, in the RL1 and RL2, respectively). CONCLUSIONS Metabolic parameters measured during exercise challenge by dynamic (31)P MRS do not depend upon the magnetic field strength used. For multicenter studies with different ergometers, it is important to set the same workload, measurement, and evaluation protocols, especially when the effects of very mild exercise (15% MVC) are to be compared. However, a higher workload (24% MVC) decreases the influence of imperfections and intersite differences for the assessed value of maximal mitochondrial capacity.
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Affiliation(s)
- Petr Šedivý
- MR-Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague 140 21, Czech Republic
| | - Monika Christina Kipfelsberger
- High-Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria and Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna A-1090, Austria
| | - Monika Dezortová
- MR-Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague 140 21, Czech Republic
| | - Martin Krššák
- High-Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria; Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna A-1090, Austria; and Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna A-1090, Austria
| | - Miloslav Drobný
- MR-Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague 140 21, Czech Republic
| | - Marek Chmelík
- High-Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria and Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna A-1090, Austria
| | - Jan Rydlo
- MR-Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague 140 21, Czech Republic
| | - Siegfried Trattnig
- High-Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria and Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna A-1090, Austria
| | - Milan Hájek
- MR-Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague 140 21, Czech Republic
| | - Ladislav Valkovič
- High-Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria; Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava 841 04, Slovakia; and Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna A-1090, Austria
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Gordon JW, Dolinsky VW, Mughal W, Gordon GRJ, McGavock J. Targeting skeletal muscle mitochondria to prevent type 2 diabetes in youth. Biochem Cell Biol 2015; 93:452-65. [PMID: 26151290 DOI: 10.1139/bcb-2015-0012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The prevalence of type 2 diabetes (T2D) has increased dramatically over the past two decades, not only among adults but also among adolescents. T2D is a systemic disorder affecting every organ system and is especially damaging to the cardiovascular system, predisposing individuals to severe cardiac and vascular complications. The precise mechanisms that cause T2D are an area of active research. Most current theories suggest that the process begins with peripheral insulin resistance that precedes failure of the pancreatic β-cells to secrete sufficient insulin to maintain normoglycemia. A growing body of literature has highlighted multiple aspects of mitochondrial function, including oxidative phosphorylation, lipid homeostasis, and mitochondrial quality control in the regulation of peripheral insulin sensitivity. Whether the cellular mechanisms of insulin resistance in adults are comparable to that in adolescents remains unclear. This review will summarize both clinical and basic studies that shed light on how alterations in skeletal muscle mitochondrial function contribute to whole body insulin resistance and will discuss the evidence supporting high-intensity exercise training as a therapy to circumvent skeletal muscle mitochondrial dysfunction to restore insulin sensitivity in both adults and adolescents.
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Affiliation(s)
- Joseph W Gordon
- a Department of Human Anatomy and Cell Science, College of Nursing, Faculty of Health Sciences, University of Manitoba, The Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, John Buhler Research Centre, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada
| | - Vernon W Dolinsky
- b Department of Pharmacology and Therapeutics, The Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, John Buhler Research Centre, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada
| | - Wajihah Mughal
- c Department of Human Anatomy and Cell Science, The Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, John Buhler Research Centre, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada
| | - Grant R J Gordon
- d Hotchkiss Brain Institute, Health Research Innovation Centre, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada.,e Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Jonathan McGavock
- f Department of Pediatrics and Child Health, The Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, John Buhler Research Centre, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada
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Kemp GJ, Ahmad RE, Nicolay K, Prompers JJ. Quantification of skeletal muscle mitochondrial function by 31P magnetic resonance spectroscopy techniques: a quantitative review. Acta Physiol (Oxf) 2015; 213:107-44. [PMID: 24773619 DOI: 10.1111/apha.12307] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 12/30/2013] [Accepted: 04/23/2014] [Indexed: 12/16/2022]
Abstract
Magnetic resonance spectroscopy (MRS) can give information about cellular metabolism in vivo which is difficult to obtain in other ways. In skeletal muscle, non-invasive (31) P MRS measurements of the post-exercise recovery kinetics of pH, [PCr], [Pi] and [ADP] contain valuable information about muscle mitochondrial function and cellular pH homeostasis in vivo, but quantitative interpretation depends on understanding the underlying physiology. Here, by giving examples of the analysis of (31) P MRS recovery data, by some simple computational simulation, and by extensively comparing data from published studies using both (31) P MRS and invasive direct measurements of muscle O2 consumption in a common analytical framework, we consider what can be learnt quantitatively about mitochondrial metabolism in skeletal muscle using MRS-based methodology. We explore some technical and conceptual limitations of current methods, and point out some aspects of the physiology which are still incompletely understood.
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Affiliation(s)
- G. J. Kemp
- Department of Musculoskeletal Biology, and Magnetic Resonance and Image Analysis Research Centre; University of Liverpool; Liverpool UK
| | - R. E. Ahmad
- Department of Musculoskeletal Biology, and Magnetic Resonance and Image Analysis Research Centre; University of Liverpool; Liverpool UK
| | - K. Nicolay
- Biomedical NMR; Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven the Netherlands
| | - J. J. Prompers
- Biomedical NMR; Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven the Netherlands
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West MA, Loughney L, Lythgoe D, Barben CP, Adams VL, Bimson WE, Grocott MPW, Jack S, Kemp GJ. The effect of neoadjuvant chemoradiotherapy on whole-body physical fitness and skeletal muscle mitochondrial oxidative phosphorylation in vivo in locally advanced rectal cancer patients--an observational pilot study. PLoS One 2014; 9:e111526. [PMID: 25478898 PMCID: PMC4257525 DOI: 10.1371/journal.pone.0111526] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 09/26/2014] [Indexed: 11/18/2022] Open
Abstract
Background In the United Kingdom, patients with locally advanced rectal cancer routinely receive neoadjuvant chemoradiotherapy. However, the effects of this on physical fitness are unclear. This pilot study is aimed to investigate the effect of neoadjuvant chemoradiotherapy on objectively measured in vivo muscle mitochondrial function and whole-body physical fitness. Methods We prospectively studied 12 patients with rectal cancer who completed standardized neoadjuvant chemoradiotherapy, recruited from a large tertiary cancer centre, between October 2012 and July 2013. All patients underwent a cardiopulmonary exercise test and a phosphorus magnetic resonance spectroscopy quadriceps muscle exercise-recovery study before and after neoadjuvant chemoradiotherapy. Data were analysed and reported blind to patient identity and clinical course. Primary variables of interest were the two physical fitness measures; oxygen uptake at estimated anaerobic threshold and oxygen uptake at Peak exercise (ml.kg−1.min−1), and the post-exercise phosphocreatine recovery rate constant (min−1), a measure of muscle mitochondrial capacity in vivo. Results Median age was 67 years (IQR 64–75). Differences (95%CI) in all three primary variables were significantly negative post-NACRT: Oxygen uptake at estimated anaerobic threshold −2.4 ml.kg−1.min−1 (−3.8, −0.9), p = 0.004; Oxygen uptake at Peak −4.0 ml.kg−1.min−1 (−6.8, −1.1), p = 0.011; and post-exercise phosphocreatine recovery rate constant −0.34 min−1 (−0.51, −0.17), p<0.001. Conclusion The significant decrease in both whole-body physical fitness and in vivo muscle mitochondrial function raises the possibility that muscle mitochondrial mechanisms, no doubt multifactorial, may be important in deterioration of physical fitness following neoadjuvant chemoradiotherapy. This may have implications for targeted interventions to improve physical fitness pre-surgery. Trial Registration Clinicaltrials.gov registration NCT01859442
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Affiliation(s)
- Malcolm A. West
- Colorectal Surgery Research Group, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
- Department of Musculoskeletal Biology and MRC – Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
- Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| | - Lisa Loughney
- Colorectal Surgery Research Group, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Southampton, United Kingdom
- Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Daniel Lythgoe
- Cancer Research UK Liverpool Cancer Trials Unit, University of Liverpool, Liverpool, United Kingdom
| | - Christopher P. Barben
- Colorectal Surgery Research Group, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
| | - Valerie L. Adams
- Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Liverpool, United Kingdom
| | - William E. Bimson
- Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Liverpool, United Kingdom
| | - Michael P. W. Grocott
- Colorectal Surgery Research Group, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
- Department of Musculoskeletal Biology and MRC – Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Southampton, United Kingdom
- Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
- Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Sandy Jack
- Colorectal Surgery Research Group, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
- Department of Musculoskeletal Biology and MRC – Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Southampton, United Kingdom
- Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
- Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Graham J. Kemp
- Department of Musculoskeletal Biology and MRC – Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
- Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Liverpool, United Kingdom
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Ectopic lipid storage in non-alcoholic fatty liver disease is not mediated by impaired mitochondrial oxidative capacity in skeletal muscle. Clin Sci (Lond) 2014; 127:655-63. [PMID: 24738611 DOI: 10.1042/cs20130404] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Non-alcoholic fatty liver disease (NAFLD), characterized by lipid deposition within the liver [intrahepatocellular lipid (IHCL)], is associated with insulin resistance and the metabolic syndrome (MS). It has been suggested that impaired skeletal muscle mitochondrial function may contribute to ectopic lipid deposition, and the associated MS, by altering post-prandial energy storage. To test this hypothesis, we performed a cross-sectional study of 17 patients with NAFLD [mean±S.D.; age, 45±11 years; body mass index (BMI), 31.6±3.4 kg/m2] and 18 age- and BMI-matched healthy controls (age, 44±11 years; BMI, 30.5±5.2 kg/m2). We determined body composition by MRI, IHCL and intramyocellular (soleus and tibialis anterior) lipids (IMCLs) by proton magnetic resonance spectroscopy (1H-MRS) and skeletal muscle mitochondrial function by dynamic phosphorus magnetic resonance spectroscopy (31P-MRS) of quadriceps muscle. Although matched for BMI and total adiposity, after statistical adjustment for gender, patients with NAFLD (defined by IHCL ≥ 5.5%) had higher IHCLs (25±16% compared with 2±2%; P<0.0005) and a higher prevalence of the MS (76% compared with 28%) compared with healthy controls. Despite this, the visceral fat/subcutaneous fat ratio, IMCLs and muscle mitochondrial function were similar between the NAFLD and control groups, with no significant difference in the rate constants of post-exercise phosphocreatine (PCr) recovery (1.55±0.4 compared with 1.51±0.4 min-1), a measure of muscle mitochondrial function. In conclusion, impaired muscle mitochondrial function does not seem to underlie ectopic lipid deposition, or the accompanying features of the MS, in patients with NAFLD.
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Prompers JJ, Wessels B, Kemp GJ, Nicolay K. MITOCHONDRIA: investigation of in vivo muscle mitochondrial function by 31P magnetic resonance spectroscopy. Int J Biochem Cell Biol 2014; 50:67-72. [PMID: 24569118 DOI: 10.1016/j.biocel.2014.02.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 02/06/2014] [Accepted: 02/16/2014] [Indexed: 01/06/2023]
Abstract
The most important function of mitochondria is the production of energy in the form of ATP. The socio-economic impact of human diseases that affect skeletal muscle mitochondrial function is growing, and improving their clinical management critically depends on the development of non-invasive assays to assess mitochondrial function and monitor the effects of interventions. 31P magnetic resonance spectroscopy provides two approaches that have been used to assess in vivo ATP synthesis in skeletal muscle: measuring Pi→ATP exchange flux using saturation transfer in resting muscle, and measuring phosphocreatine recovery kinetics after exercise. However, Pi→ATP exchange does not represent net mitochondrial ATP synthesis flux and has no simple relationship with mitochondrial function. Post-exercise phosphocreatine recovery kinetics, on the other hand, yield reliable measures of muscle mitochondrial capacity in vivo, whose ability to define the site of functional defects is enhanced by combination with other non-invasive techniques.
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Affiliation(s)
- Jeanine J Prompers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
| | - Bart Wessels
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Graham J Kemp
- Department of Musculoskeletal Biology and Magnetic Resonance & Image Analysis Research Centre, University of Liverpool, UK
| | - Klaas Nicolay
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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13
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Abstract
Magnetic resonance spectroscopy (MRS) methods offer a potentially valuable window into cellular metabolism. Measurement of flux between inorganic phosphate (Pi) and ATP using (31)P MRS magnetization transfer has been used in resting muscle to assess what is claimed to be mitochondrial ATP synthesis and has been particularly popular in the study of insulin effects and insulin resistance. However, the measured Pi→ATP flux in resting skeletal muscle is far higher than the true rate of oxidative ATP synthesis, being dominated by a glycolytically mediated Pi↔ATP exchange reaction that is unrelated to mitochondrial function. Furthermore, even if measured accurately, the ATP production rate in resting muscle has no simple relationship to mitochondrial capacity as measured either ex vivo or in vivo. We summarize the published measurements of Pi→ATP flux, concentrating on work relevant to diabetes and insulin, relate it to current understanding of the physiology of mitochondrial ATP synthesis and glycolytic Pi↔ATP exchange, and discuss some possible implications of recently reported correlations between Pi→ATP flux and other physiological measures.
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Affiliation(s)
- Graham J Kemp
- Department of Musculoskeletal Biology and Magnetic Resonance and Image Analysis Research Centre, University of Liverpool, Liverpool, UK.
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Schmitz JPJ, Jeneson JAL, van Oorschot JWM, Prompers JJ, Nicolay K, Hilbers PAJ, van Riel NAW. Prediction of muscle energy states at low metabolic rates requires feedback control of mitochondrial respiratory chain activity by inorganic phosphate. PLoS One 2012; 7:e34118. [PMID: 22470528 PMCID: PMC3314597 DOI: 10.1371/journal.pone.0034118] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 02/22/2012] [Indexed: 01/20/2023] Open
Abstract
The regulation of the 100-fold dynamic range of mitochondrial ATP synthesis flux in skeletal muscle was investigated. Hypotheses of key control mechanisms were included in a biophysical model of oxidative phosphorylation and tested against metabolite dynamics recorded by (31)P nuclear magnetic resonance spectroscopy ((31)P MRS). Simulations of the initial model featuring only ADP and Pi feedback control of flux failed in reproducing the experimentally sampled relation between myoplasmic free energy of ATP hydrolysis (ΔG(p) = ΔG(p)(o')+RT ln ([ADP][Pi]/[ATP]) and the rate of mitochondrial ATP synthesis at low fluxes (<0.2 mM/s). Model analyses including Monte Carlo simulation approaches and metabolic control analysis (MCA) showed that this problem could not be amended by model re-parameterization, but instead required reformulation of ADP and Pi feedback control or introduction of additional control mechanisms (feed forward activation), specifically at respiratory Complex III. Both hypotheses were implemented and tested against time course data of phosphocreatine (PCr), Pi and ATP dynamics during post-exercise recovery and validation data obtained by (31)P MRS of sedentary subjects and track athletes. The results rejected the hypothesis of regulation by feed forward activation. Instead, it was concluded that feedback control of respiratory chain complexes by inorganic phosphate is essential to explain the regulation of mitochondrial ATP synthesis flux in skeletal muscle throughout its full dynamic range.
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Affiliation(s)
- Joep P J Schmitz
- BioModeling and Bioinformatics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
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Lanza IR, Bhagra S, Nair KS, Port JD. Measurement of human skeletal muscle oxidative capacity by 31P-MR spectroscopy: a cross-validation with in vitro measurements. J Magn Reson Imaging 2012; 34:1143-50. [PMID: 22006551 DOI: 10.1002/jmri.22733] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
PURPOSE To cross-validate skeletal muscle oxidative capacity measured by (31)P-MR spectroscopy with in vitro measurements of oxidative capacity in mitochondria isolated from muscle biopsies of the same muscle group in 18 healthy adults. MATERIALS AND METHODS Oxidative capacity in vivo was determined from PCr recovery kinetics following a 30-s maximal isometric knee extension. State 3 respiration was measured in isolated mitochondria using high-resolution respirometry. A second cohort of 10 individuals underwent two (31)P-MRS testing sessions to assess the test-retest reproducibility of the method. RESULTS Overall, the in vivo and in vitro methods were well-correlated (r = 0.66-0.72) and showed good agreement by Bland Altman plots. Excellent reproducibility was observed for the PCr recovery rate constant (CV = 4.6%; ICC = 0.85) and calculated oxidative capacity (CV = 3.4%; ICC = 0.83). CONCLUSION These results indicate that (31)P-MRS corresponds well with gold-standard in vitro measurements and is highly reproducible.
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Affiliation(s)
- Ian R Lanza
- Division of Endocrinology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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Jonkers RAM, Dirks ML, Nabuurs CIHC, De Feyter HM, Praet SFE, Nicolay K, van Loon LJC, Prompers JJ. Myofibrillar distribution of succinate dehydrogenase activity and lipid stores differs in skeletal muscle tissue of paraplegic subjects. Am J Physiol Endocrinol Metab 2012; 302:E365-73. [PMID: 22068603 DOI: 10.1152/ajpendo.00270.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Lack of physical activity has been related to an increased risk of developing insulin resistance. This study aimed to assess the impact of chronic muscle deconditioning on whole body insulin sensitivity, muscle oxidative capacity, and intramyocellular lipid (IMCL) content in subjects with paraplegia. Nine subjects with paraplegia and nine able-bodied, lean controls were recruited. An oral glucose tolerance test was performed to assess whole body insulin sensitivity. IMCL content was determined both in vivo and in vitro using (1)H-magnetic resonance spectroscopy and fluorescence microscopy, respectively. Muscle biopsy samples were stained for succinate dehydrogenase (SDH) activity to measure muscle fiber oxidative capacity. Subcellular distributions of IMCL and SDH activity were determined by defining subsarcolemmal and intermyofibrillar areas on histological samples. SDH activity was 57 ± 14% lower in muscle fibers derived from subjects with paraplegia when compared with controls (P < 0.05), but IMCL content and whole body insulin sensitivity did not differ between groups. In muscle fibers taken from controls, both SDH activity and IMCL content were higher in the subsarcolemmal region than in the intermyofibrillar area. This typical subcellular SDH and IMCL distribution pattern was lost in muscle fibers collected from subjects with paraplegia and had changed toward a more uniform distribution. In conclusion, the lower metabolic demand in deconditioned muscle of subjects with paraplegia results in a significant decline in muscle fiber oxidative capacity and is accompanied by changes in the subcellular distribution patterns of SDH activity and IMCL. However, loss of muscle activity due to paraplegia is not associated with substantial lipid accumulation in skeletal muscle tissue.
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Affiliation(s)
- Richard A M Jonkers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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Trattnig S, Friedrich KM, Bogner W, Welsch GH. Advanced musculoskeletal MRI at ultra-high field (7 T). ACTA ACUST UNITED AC 2010. [DOI: 10.2217/iim.09.26] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Skeletal muscle metabolic recovery following submaximal exercise in chronic heart failure is limited more by O2 delivery than O2 utilization. Clin Sci (Lond) 2010; 118:203-10. [DOI: 10.1042/cs20090220] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
CHF (chronic heart failure) is associated with a prolonged recovery of skeletal muscle energy stores following submaximal exercise, limiting the ability to perform repetitive daily activities. However, the pathophysiological background of this impairment is not well established. The aim of the present study was to investigate whether muscle metabolic recovery following submaximal exercise in patients with CHF is limited by O2 delivery or O2 utilization. A total of 13 stable CHF patients (New York Heart Association classes II–III) and eight healthy subjects, matched for age and BMI (body mass index), were included. All subjects performed repetitive submaximal dynamic single leg extensions in the supine position. Post-exercise PCr (phosphocreatine) resynthesis was assessed by 31P-MRS (magnetic resonance spectroscopy). NIRS (near-IR spectroscopy) was applied simultaneously, using the rate of decrease in HHb (deoxygenated haemoglobin) as an index of post-exercise muscle re-oxygenation. As expected, PCr recovery was slower in CHF patients than in control subjects (time constant, 47±10 compared with 35±12 s respectively; P=0.04). HHb recovery kinetics were also prolonged in CHF patients (mean response time, 74±41 compared with 44±17 s respectively; P=0.04). In the patient group, HHb recovery kinetics were slower than PCr recovery kinetics (P=0.02), whereas no difference existed in the control group (P=0.32). In conclusion, prolonged metabolic recovery in CHF patients is associated with an even slower muscle tissue re-oxygenation, indicating a lower O2 delivery relative to metabolic demands. Therefore we postulate that the impaired ability to perform repetitive daily activities in these patients depends more on a reduced muscle blood flow than on limitations in O2 utilization.
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Hansen D, Dendale P, Jonkers RAM, Beelen M, Manders RJF, Corluy L, Mullens A, Berger J, Meeusen R, van Loon LJC. Continuous low- to moderate-intensity exercise training is as effective as moderate- to high-intensity exercise training at lowering blood HbA(1c) in obese type 2 diabetes patients. Diabetologia 2009; 52:1789-97. [PMID: 19370339 PMCID: PMC2723667 DOI: 10.1007/s00125-009-1354-3] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 03/10/2009] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS Exercise represents an effective interventional strategy to improve glycaemic control in type 2 diabetes patients. However, the impact of exercise intensity on the benefits of exercise training remains to be established. In the present study, we compared the clinical benefits of 6 months of continuous low- to moderate-intensity exercise training with those of continuous moderate- to high-intensity exercise training, matched for energy expenditure, in obese type 2 diabetes patients. METHODS Fifty male obese type 2 diabetes patients (age 59 +/- 8 years, BMI 32 +/- 4 kg/m(2)) participated in a 6 month continuous endurance-type exercise training programme. All participants performed three supervised exercise sessions per week, either 55 min at 50% of whole body peak oxygen uptake (VO(2)peak (low to moderate intensity) or 40 min at 75% of VO(2)peak (moderate to high intensity). Oral glucose tolerance, blood glycated haemoglobin, lipid profile, body composition, maximal workload capacity, whole body and skeletal muscle oxidative capacity and skeletal muscle fibre type composition were assessed before and after 2 and 6 months of intervention. RESULTS The entire 6 month intervention programme was completed by 37 participants. Continuous endurance-type exercise training reduced blood glycated haemoglobin levels, LDL-cholesterol concentrations, body weight and leg fat mass, and increased VO(2)peak, lean muscle mass and skeletal muscle cytochrome c oxidase and citrate synthase activity (p < 0.05). No differences were observed between the groups training at low to moderate or moderate to high intensity. CONCLUSIONS/INTERPRETATION When matched for energy cost, prolonged continuous low- to moderate-intensity endurance-type exercise training is equally effective as continuous moderate- to high-intensity training in lowering blood glycated haemoglobin and increasing whole body and skeletal muscle oxidative capacity in obese type 2 diabetes patients. TRIAL REGISTRATION ISRCTN32206301 FUNDING None.
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Affiliation(s)
- D. Hansen
- Department of Human Physiology and Sports Medicine, Vrije Universiteit Brussel, Brussels, Belgium
- Rehabilitation and Health Centre, Virga Jesse Hospital, Hasselt, Belgium
| | - P. Dendale
- Rehabilitation and Health Centre, Virga Jesse Hospital, Hasselt, Belgium
| | - R. A. M. Jonkers
- Department of Human Movement Sciences, Nutrition and Toxicology Research Institute (NUTRIM), Maastricht University Medical Centre+, Universiteitssingel 50, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - M. Beelen
- Department of Human Movement Sciences, Nutrition and Toxicology Research Institute (NUTRIM), Maastricht University Medical Centre+, Universiteitssingel 50, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - R. J. F. Manders
- Department of Human Movement Sciences, Nutrition and Toxicology Research Institute (NUTRIM), Maastricht University Medical Centre+, Universiteitssingel 50, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - L. Corluy
- Department of Rheumatology, Virga Jesse Hospital, Hasselt, Belgium
| | - A. Mullens
- Department of Endocrinology, Virga Jesse Hospital, Hasselt, Belgium
| | - J. Berger
- Rehabilitation and Health Centre, Virga Jesse Hospital, Hasselt, Belgium
| | - R. Meeusen
- Department of Human Physiology and Sports Medicine, Vrije Universiteit Brussel, Brussels, Belgium
| | - L. J. C. van Loon
- Department of Human Movement Sciences, Nutrition and Toxicology Research Institute (NUTRIM), Maastricht University Medical Centre+, Universiteitssingel 50, PO Box 616, 6200 MD Maastricht, The Netherlands
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Muscle Mitochondrial Function in Patients with Type 2 Diabetes Mellitus and Peripheral Arterial Disease: Implications in Vascular Surgery. Eur J Vasc Endovasc Surg 2009; 38:356-64. [DOI: 10.1016/j.ejvs.2009.04.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Accepted: 04/20/2009] [Indexed: 11/23/2022]
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Jones AM, Wilkerson DP, Fulford J. Muscle [phosphocreatine] dynamics following the onset of exercise in humans: the influence of baseline work-rate. J Physiol 2007; 586:889-98. [PMID: 18063663 DOI: 10.1113/jphysiol.2007.142026] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The kinetics of pulmonary O(2) uptake is known to be substantially slower when exercise is initiated from a baseline of lower-intensity exercise rather than from rest. However, it is not known whether putative intracellular regulators of mitochondrial respiration (and in particular the phosphocreatine concentration, [PCr]) show similar non-linearities in their response dynamics. The purpose of this study was therefore to investigate the influence of baseline metabolic rate on muscle [PCr] kinetics (as assessed using (31)P-magnetic resonance spectroscopy) following the onset of exercise. Seven male subjects completed 'step' tests to heavy-intensity exercise (80% of peak work-rate) from a resting baseline and also from a baseline of moderate-intensity exercise (40% of peak work-rate) using a single-leg knee-extensor ergometer situated inside the bore of a 1.5 T super-conducting magnet. The time constant describing the kinetics of the initial exponential-like fall in [PCr] was significantly different between rest-to-moderate (25 +/- 14 s), rest-to-heavy (48 +/- 11 s) and moderate-to-heavy exercise (95 +/- 40 s) (P < 0.05 for all comparisons). A delayed-onset 'slow component' in the [PCr] response was observed in all subjects during rest-to-heavy exercise, but was attenuated in the moderate-to-heavy exercise condition. These data indicate that muscle [PCr] kinetics does not conform to 'linear, first-order' behaviour during dynamic exercise, and thus have implications for understanding the regulation of muscle oxidative metabolism.
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Affiliation(s)
- Andrew M Jones
- School of Sport and Health Sciences, St Luke's Campus, University of Exeter, Heavitree Road, Exeter EX1 2LU, UK.
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Abstract
PURPOSE OF REVIEW Clinical investigations of neuromuscular diseases routinely involve genetic, neurophysiological, biochemical and histopathological methods. More recently, various magnetic resonance imaging techniques have become available and extended the differential diagnostic possibilities. RECENT FINDINGS Using magnetic resonance imaging it is now possible to quantify muscle volume in selected body regions and measure wasting and exercise-induced muscle hypertrophy. Evidence is forthcoming that many hereditary myopathies are characterized by distinct patterns of muscle degeneration and this helps in selecting other relevant genetic and biochemical investigations. With diffusion-weighted tensor imaging it is possible to identify the microstructure of normal and diseased muscles. Arterial spin labelling is an emerging non-invasive tool to assess blood-flow changes in individual muscles. Magnetic resonance spectroscopy now provides an exciting opportunity to visualize metabolic changes and the pathophysiologically relevant cellular perturbations in muscle channelopathies affecting the muscle-specific sodium-channel isoform Na(v)1.4. SUMMARY Magnetic resonance imaging supplements investigations for the differential diagnosis of neuromuscular diseases. An advantage over routine neurophysiological or histopathological methods is that they are operator-independent, non-invasive and painless. Magnetic resonance imaging also has the advantage of providing a lasting detailed topographical picture of regional variations and allows robust measurements of muscle volume and various functional parameters.
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De Feyter HM, Praet SF, van den Broek NM, Kuipers H, Stehouwer CD, Nicolay K, Prompers JJ, van Loon LJC. Exercise training improves glycemic control in long-standing insulin-treated type 2 diabetic patients. Diabetes Care 2007; 30:2511-3. [PMID: 17626892 DOI: 10.2337/dc07-0183] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Henk M De Feyter
- Department of Biomedical NMR, Eindhoven University of Technology, Eindhoven, The Netherlands
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