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Packer M, Anker SD, Butler J, Cleland JGF, Kalra PR, Mentz RJ, Ponikowski P. Identification of three mechanistic pathways for iron-deficient heart failure. Eur Heart J 2024:ehae284. [PMID: 38733250 DOI: 10.1093/eurheartj/ehae284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 02/29/2024] [Accepted: 04/23/2024] [Indexed: 05/13/2024] Open
Abstract
Current understanding of iron-deficient heart failure is based on blood tests that are thought to reflect systemic iron stores, but the available evidence suggests greater complexity. The entry and egress of circulating iron is controlled by erythroblasts, which (in severe iron deficiency) will sacrifice erythropoiesis to supply iron to other organs, e.g. the heart. Marked hypoferraemia (typically with anaemia) can drive the depletion of cardiomyocyte iron, impairing contractile performance and explaining why a transferrin saturation < ≈15%-16% predicts the ability of intravenous iron to reduce the risk of major heart failure events in long-term trials (Type 1 iron-deficient heart failure). However, heart failure may be accompanied by intracellular iron depletion within skeletal muscle and cardiomyocytes, which is disproportionate to the findings of systemic iron biomarkers. Inflammation- and deconditioning-mediated skeletal muscle dysfunction-a primary cause of dyspnoea and exercise intolerance in patients with heart failure-is accompanied by intracellular skeletal myocyte iron depletion, which can be exacerbated by even mild hypoferraemia, explaining why symptoms and functional capacity improve following intravenous iron, regardless of baseline haemoglobin or changes in haemoglobin (Type 2 iron-deficient heart failure). Additionally, patients with advanced heart failure show myocardial iron depletion due to both diminished entry into and enhanced egress of iron from the myocardium; the changes in iron proteins in the cardiomyocytes of these patients are opposite to those expected from systemic iron deficiency. Nevertheless, iron supplementation can prevent ventricular remodelling and cardiomyopathy produced by experimental injury in the absence of systemic iron deficiency (Type 3 iron-deficient heart failure). These observations, taken collectively, support the possibility of three different mechanistic pathways for the development of iron-deficient heart failure: one that is driven through systemic iron depletion and impaired erythropoiesis and two that are characterized by disproportionate depletion of intracellular iron in skeletal and cardiac muscle. These mechanisms are not mutually exclusive, and all pathways may be operative at the same time or may occur sequentially in the same patients.
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Affiliation(s)
- Milton Packer
- Baylor Heart and Vascular Institute, Baylor University Medical Center, 621 North Hall Street, Dallas, TX 75226, USA
- Imperial College, London, UK
| | - Stefan D Anker
- Department of Cardiology of German Heart Center Charité, Institute of Health Center for Regenerative Therapies, German Centre for Cardiovascular Research, partner site Berlin, Charité Universitätsmedizin, Berlin, Germany
| | - Javed Butler
- Baylor Scott and White Research Institute, Baylor University Medical Center, Dallas, TX, USA
- University of Mississippi Medical Center, Jackson, MS, USA
| | - John G F Cleland
- British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Paul R Kalra
- Department of Cardiology, Portsmouth Hospitals University NHS Trust, Portsmouth, UK
- College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
- Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Robert J Mentz
- Division of Cardiology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
- Duke Clinical Research Institute, Durham, NC, USA
| | - Piotr Ponikowski
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Institute of Heart Diseases, University Hospital, Wroclaw, Poland
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2
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Frise MC, Holdsworth DA, Johnson AW, Chung YJ, Curtis MK, Cox PJ, Clarke K, Tyler DJ, Roberts DJ, Ratcliffe PJ, Dorrington KL, Robbins PA. Abnormal whole-body energy metabolism in iron-deficient humans despite preserved skeletal muscle oxidative phosphorylation. Sci Rep 2022; 12:998. [PMID: 35046429 PMCID: PMC8770476 DOI: 10.1038/s41598-021-03968-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 12/10/2021] [Indexed: 01/01/2023] Open
Abstract
Iron deficiency impairs skeletal muscle metabolism. The underlying mechanisms are incompletely characterised, but animal and human experiments suggest the involvement of signalling pathways co-dependent upon oxygen and iron availability, including the pathway associated with hypoxia-inducible factor (HIF). We performed a prospective, case-control, clinical physiology study to explore the effects of iron deficiency on human metabolism, using exercise as a stressor. Thirteen iron-deficient (ID) individuals and thirteen iron-replete (IR) control participants each underwent 31P-magnetic resonance spectroscopy of exercising calf muscle to investigate differences in oxidative phosphorylation, followed by whole-body cardiopulmonary exercise testing. Thereafter, individuals were given an intravenous (IV) infusion, randomised to either iron or saline, and the assessments repeated ~ 1 week later. Neither baseline iron status nor IV iron significantly influenced high-energy phosphate metabolism. During submaximal cardiopulmonary exercise, the rate of decline in blood lactate concentration was diminished in the ID group (P = 0.005). Intravenous iron corrected this abnormality. Furthermore, IV iron increased lactate threshold during maximal cardiopulmonary exercise by ~ 10%, regardless of baseline iron status. These findings demonstrate abnormal whole-body energy metabolism in iron-deficient but otherwise healthy humans. Iron deficiency promotes a more glycolytic phenotype without having a detectable effect on mitochondrial bioenergetics.
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Affiliation(s)
- Matthew C Frise
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - David A Holdsworth
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Andrew W Johnson
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Yu Jin Chung
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - M Kate Curtis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Pete J Cox
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - David J Roberts
- Nuffield Department of Clinical Laboratory Sciences, National Blood Service Oxford Centre, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9BQ, UK
| | - Peter J Ratcliffe
- Nuffield Department of Medicine, University of Oxford, NDM Research Building, Old Road Campus, Headington, Oxford, OX3 7FZ, UK
- Francis Crick Institute, London, NW1 1AT, UK
| | - Keith L Dorrington
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Peter A Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK.
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Melenovsky V, Hlavata K, Sedivy P, Dezortova M, Borlaug BA, Petrak J, Kautzner J, Hajek M. Skeletal Muscle Abnormalities and Iron Deficiency in Chronic Heart Failure An Exercise 31P Magnetic Resonance Spectroscopy Study of Calf Muscle. Circ Heart Fail 2019; 11:e004800. [PMID: 30354361 DOI: 10.1161/circheartfailure.117.004800] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Heart failure (HF) is often associated with iron deficiency (ID). Skeletal muscle abnormalities are common in HF, but the potential role of ID in this phenomenon is unclear. In addition to hemopoiesis, iron is essential for muscle bioenergetics. We examined whether energetic abnormalities in skeletal muscle in HF are affected by ID and if they are responsive to intravenous iron. METHODS AND RESULTS Forty-four chronic HF subjects and 25 similar healthy volunteers underwent 31P magnetic resonance spectroscopy of calf muscle at rest and during exercise (plantar flexions). Results were compared between HF subjects with or without ID. In 13 ID-HF subjects, examinations were repeated 1 month after intravenous ferric carboxymaltose administration (1000 mg). As compared with controls, HF subjects displayed lower resting high-energy phosphate content, lower exercise pH, and slower postexercise PCr recovery. Compared with non-ID HF, ID-HF subjects had lower muscle strength, larger PCr depletion, and more profound intracellular acidosis with exercise, consistent with an earlier metabolic shift to anaerobic glycolysis. The exercise-induced PCr drop strongly correlated with pH change in HF group ( r=-0.71, P<0.001) but not in controls ( r=0.13, P=0.61, interaction: P<0.0001). Short-term iron administration corrected the iron deficit but had no effect on muscle bioenergetics assessed 1 month later. CONCLUSIONS HF patients display skeletal muscle myopathy that is more severe in those with iron deficiency. The presence of ID is associated with greater acidosis with exercise, which may explain early muscle fatigue. Further study is warranted to identify the strategy to restore iron content in skeletal muscle.
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Affiliation(s)
- Vojtech Melenovsky
- Department of Cardiology, Institute for Clinical and Experimental Medicine, IKEM, Prague, Czech Republic (V.M., K.H., J.K.)
| | - Katerina Hlavata
- Department of Cardiology, Institute for Clinical and Experimental Medicine, IKEM, Prague, Czech Republic (V.M., K.H., J.K.)
| | - Petr Sedivy
- Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, IKEM, Prague, Czech Republic (P.S., M.D., M.H.)
| | - Monika Dezortova
- Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, IKEM, Prague, Czech Republic (P.S., M.D., M.H.)
| | - Barry A Borlaug
- Department of Cardiovascular Disease, Mayo Clinic, Rochester, MN (B.A.B.)
| | - Jiri Petrak
- Department of Cardiology, Institute for Clinical and Experimental Medicine, IKEM, Prague, Czech Republic (V.M., K.H., J.K.)
| | - Josef Kautzner
- BIOCEV, First Faculty of Medicine, Charles University, Vestec, Czech Republic (J.P.)
| | - Milan Hajek
- Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, IKEM, Prague, Czech Republic (P.S., M.D., M.H.)
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Boban M, Barisic M, Persic V, Zekanovic D, Medved I, Zulj M, Vcev A. Muscle strength differ between patients with diabetes and controls following heart surgery. J Diabetes Complications 2016; 30:1287-92. [PMID: 27368124 DOI: 10.1016/j.jdiacomp.2016.06.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 05/20/2016] [Accepted: 06/04/2016] [Indexed: 01/16/2023]
Abstract
BACKGROUND The aim of our study was to analyze muscle strength in patients with recent surgical treatment for ischemic and combined ischemic-valvular heart disease, based on existence of diabetes mellitus. Connections existing between muscle strength and patient characteristics or conventional diagnostic tests were analyzed as well. METHODS Study prospectively included consecutive patients scheduled for cardiovascular rehabilitation 0-3months after heart surgery. Diagnostics covered drug utilization, anthropometrics, demographics, echocardiography, conventional laboratory, echocardiography, bioelectrical impedance analysis (BIA), and hand grip test (HGT). HGT was analyzed for dominant hand. RESULTS Patients with diabetes had significantly weaker muscle strength on HGT than controls; 29.4±12.2kg vs. 38.2±14.7kg (p=0.029), respectively. ROC analysis for HGT and existence of diabetes mellitus were significant; ≤40kg had sensitivity of 89.7% (95%CI: 72.6-97.8), specificity 43.7% (31.9-56.0); AUC 0.669 (0.568-0.760); p=0.002. HGT significantly correlated with hematocrit (Rho CC=0.247; p=0.013), whilst other laboratory or echocardiographic parameters were insignificant (all p>0.05). HGT also correlated with body weight (Rho CC=0.510; p<0.001); height (Rho CC=0.632; p<0.001); waist circumference (Rho CC=0.388; p<0.001); waist-to-hip ratio (Rho CC=0.274; p=0.006) and BIA (Rho CC=-0.412; p<0.001). CONCLUSIONS In postoperative recovery of patients with diabetes, muscle strength assessed by HGT is decreased and in relation with nutritional status. Clinically resourceful connections of HGT were also found to hematocrit and utilization of loop diuretics.
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Affiliation(s)
- Marko Boban
- Department of Cardiology, University Hospital "Thalassotherapia Opatija", Medical Faculty University of Rijeka, Croatia; Department of Internal Medicine, Medical Faculty "J.J. Strossmayer" University of Osijek, Croatia.
| | - Mijana Barisic
- Department of Cardiology, University Hospital "Thalassotherapia Opatija", Medical Faculty University of Rijeka, Croatia
| | - Viktor Persic
- Department of Cardiology, University Hospital "Thalassotherapia Opatija", Medical Faculty University of Rijeka, Croatia; Department of Internal Medicine, Medical Faculty "J.J. Strossmayer" University of Osijek, Croatia
| | | | - Igor Medved
- Department of Cardiac Surgery, Medical Faculty University of Rijeka, University Hospital Centre "Rijeka", Croatia
| | - Marinko Zulj
- Department of Internal Medicine, Medical Faculty "J.J. Strossmayer" University of Osijek, Croatia
| | - Aleskandar Vcev
- Department of Internal Medicine, Medical Faculty "J.J. Strossmayer" University of Osijek, Croatia
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Saraon T, Katz SD. Targeting Iron Deficiency Anemia in Heart Failure. Prog Cardiovasc Dis 2015; 58:407-15. [PMID: 26657161 DOI: 10.1016/j.pcad.2015.11.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 11/27/2015] [Indexed: 12/12/2022]
Abstract
Iron deficiency is common in heart failure (HF) patients, and is associated with increased risk of adverse clinical outcomes. Clinical trials of intravenous iron supplementation in iron-deficient HF patients have demonstrated short-term improvement in functional capacity and quality of life. In some trials, the benefits of iron supplementation were independent of the hemoglobin levels. Additional investigations of iron supplementation are needed to characterize the mechanisms contributing to clinical benefit and long-term safety in HF.
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Affiliation(s)
- Tajinderpal Saraon
- Leon H. Charney Division of Cardiology, New York University Langone Medical Center, New York, NY
| | - Stuart D Katz
- Leon H. Charney Division of Cardiology, New York University Langone Medical Center, New York, NY.
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6
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Estimated contribution of hemoglobin and myoglobin to near infrared spectroscopy. Respir Physiol Neurobiol 2013; 186:180-7. [DOI: 10.1016/j.resp.2013.01.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Revised: 12/14/2012] [Accepted: 01/21/2013] [Indexed: 11/20/2022]
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Bekedam MA, van Beek-Harmsen BJ, van Mechelen W, Boonstra A, van der Laarse WJ. Myoglobin concentration in skeletal muscle fibers of chronic heart failure patients. J Appl Physiol (1985) 2009; 107:1138-43. [PMID: 19661455 DOI: 10.1152/japplphysiol.00149.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to determine the myoglobin concentration in skeletal muscle fibers of chronic heart failure (CHF) patients and to calculate the effect of myoglobin on oxygen buffering and facilitated diffusion. Myoglobin concentration, succinate dehydrogenase (SDH) activity, and cross-sectional area of individual muscle fibers from the vastus lateralis of five control and nine CHF patients were determined using calibrated histochemistry. CHF patients compared with control subjects were similar with respect to myoglobin concentration: type I fibers 0.69 +/- 0.11 mM (mean +/- SD), type II fibers 0.52 +/- 0.07 mM in CHF vs. type I fibers 0.70 +/- 0.09 mM, type II fibers 0.49 +/- 0.07 mM in control, whereas SDH activity was significantly lower in CHF in both fiber types (P < 0.01). The myoglobin concentration in type I fibers was higher than in type II fibers (P < 0.01). Consequently, the oxygen buffering capacity, calculated from myoglobin concentration/SDH activity was increased in CHF: type I fibers 11.4 +/- 2.1 s, type II fibers 13.6 +/- 3.9 s in CHF vs. type I fibers 7.8 +/- 0.9 s, type II fibers 7.5 +/- 1.0 s in control, all P < 0.01). The calculated extracellular oxygen tension required to prevent core anoxia (Po2(crit)) in muscle fibers was similar when controls were compared with patients in type I fibers 10.3 +/- 0.9 Torr in CHF and 11.5 +/- 3.3 Torr in control, but was lower in type II fibers of patients 6.1 +/- 2.8 Torr in CHF and 14.7 +/- 6.2 Torr in control, P < 0.01. The lower Po2(crit) of type II fibers may facilitate oxygen extraction from capillaries. Reduced exercise tolerance in CHF is not due to myoglobin deficiency.
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Affiliation(s)
- Martijn A Bekedam
- Department of Physiology, Van der Boechorststraat 7, 1081 BT, Amsterdam, The Netherlands
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8
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Esteva S, Panisello P, Casas M, Torrella JR, Pagés T, Viscor G. Morphofunctional responses to anaemia in rat skeletal muscle. J Anat 2008; 212:836-44. [PMID: 18510510 PMCID: PMC2423404 DOI: 10.1111/j.1469-7580.2008.00908.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2008] [Indexed: 11/26/2022] Open
Abstract
Adult male Sprague-Dawley rats were randomly assigned to two groups: control and anaemic. Anaemia was induced by periodical blood withdrawal. Extensor digitorum longus and soleus muscles were excised under pentobarbital sodium total anaesthesia and processed for transmission electron microscopy, histochemical and biochemical analyses. Mitochondrial volume was determined by transmission electron microscopy in three different regions of each muscle fibre: pericapillary, sarcolemmal and sarcoplasmatic. Muscle samples sections were also stained with histochemical methods (SDH and m-ATPase) to reveal the oxidative capacity and shortening velocity of each muscle fibre. Determinations of fibre and capillary densities and fibre type composition were made from micrographs of different fixed fields selected in the equatorial region of each rat muscle. Determination of metabolites (ATP, inorganic phosphate, creatine, creatine phosphate and lactate) was done using established enzymatic methods and spectrophotometric detection. Significant differences in mitochondrial volumes were found between pericapillary, sarcolemmal and sarcoplasmic regions when data from animal groups were tested independently. Moreover, it was verified that anaemic rats had significantly lower values than control animals in all the sampled regions of both muscles. These changes were associated with a significantly higher proportion of fast fibres in anaemic rat soleus muscles (slow oxidative group = 63.8%; fast glycolytic group = 8.2%; fast oxidative glycolytic group = 27.4%) than in the controls (slow oxidative group = 79.0%; fast glycolytic group = 3.9%; fast oxidative glycolytic group = 17.1%). No significant changes were detected in the extensor digitorum longus muscle. A significant increase was found in metabolite concentration in both the extensor digitorum longus and soleus muscles of the anaemic animals as compared to the control group. In conclusion, hypoxaemic hypoxia causes a reduction in mitochondrial volumes of pericapillary, sarcolemmal, and sarcoplasmic regions. However, a common proportional pattern of the zonal distribution of mitochondria was maintained within the fibres. A significant increment was found in the concentration of some metabolites and in the proportion of fast fibres in the more oxidative soleus muscle in contrast to the predominantly anaerobic extensor digitorum longus.
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Affiliation(s)
- Santiago Esteva
- Departament de Fisiologia - Biologia, Universitat de Barcelona, Spain
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10
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Abstract
Nutritional iron deficiency (ID) is caused by an intake of dietary iron insufficient to cover physiological iron requirements. Studies on iron absorption from whole diets have examined relationships between dietary iron bioavailability/absorption, iron losses, and amounts of stored iron. New insights have been obtained into regulation of iron absorption and expected rates of changes of iron stores or hemoglobin iron deficits when bioavailability or iron content of the diet has been modified and when losses of iron occur. Negative effects of ID are probably related to age, up to about 20 years, explaining some of earlier controversies. Difficulties in establishing the prevalence of mild ID are outlined. The degree of underestimation of the prevalence of mild ID when using multiple diagnostic criteria is discussed. It is suggested that current low-energy lifestyles are a common denominator for the current high prevalence not only of ID but also of obesity, diabetes, and osteoporosis.
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Affiliation(s)
- L Hallberg
- Department of Clinical Nutrition, Göteborg University, Sahlgrenska, University Hospital, Annedalsklinikerna, Göteborg, SE-413 45 Sweden.
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Thompson CH, Kemp GJ, Taylor DJ, Radda GK, Rajagopalan B. No evidence of mitochondrial abnormality in skeletal muscle of patients with iron-deficient anaemia. J Intern Med 1993; 234:149-54. [PMID: 8340737 DOI: 10.1111/j.1365-2796.1993.tb00724.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVES Patients with iron deficiency anaemia complain of decreased exercise capacity. We asked whether this is due to defective oxidative ATP synthesis in skeletal muscle as a consequence of reduced blood oxygen content and/or intrinsic mitochondrial abnormalities. DESIGN We used 31P magnetic resonance spectroscopy to examine skeletal muscle bioenergetics in iron-deficient patients and in age- and sex-matched controls. SETTING The patients were recruited from the primary care population. SUBJECTS We studied seven symptomatic female iron-deficient patients (aged 32-70 years) with haemoglobin (Hb) concentration, [Hb], 8.0 g dl-1. Six had menorrhagia, the cause in the seventh patient remained undiagnosed. Results were compared with those of 8 healthy female controls (aged 25-48 years) with mean [Hb] 13.7 g dl-1. RESULTS The right calf muscle was by studied 31P magnetic resonance spectroscopy in a 1.9 T super-conducting magnet. We measured the intracellular concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), adenosine triphosphate (ATP) and the intracellular pH at rest, during plantar flexion exercise and during recovery from exercise. Exercise duration was reduced in the patients, yet end-exercise PCr/(PCr+Pi) was higher and adenosine diphosphate (ADP) lower than in controls. After exercise, initial PCr recovery was slowed but this was probably because of the lower cytosolic ADP concentration. CONCLUSIONS Mitochondrial ATP synthesis was not limited by oxygen supply or an intrinsic mitochondrial defect. Therefore, the reduced exercise capacity seen in iron deficiency could be due to central causes and not to skeletal muscle metabolic abnormalities.
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Affiliation(s)
- C H Thompson
- MRC Biochemical and Clinical Magnetic Resonance Unit, John Radcliffe Hospital, Oxford, UK
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12
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Thompson CH, Green YS, Ledingham JG, Radda GK, Rajagopalan B. The effect of iron deficiency on skeletal muscle metabolism of the rat. ACTA PHYSIOLOGICA SCANDINAVICA 1993; 147:85-90. [PMID: 8452045 DOI: 10.1111/j.1748-1716.1993.tb09475.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Using 31P magnetic resonance spectroscopy we compared skeletal muscle bioenergetics in Wistar rats made chronically anaemic by being fed a diet deficient in iron for 6 weeks with chronically iron deficient animals given a normal diet as well as 5 mg iron dextran at 2 or 7 days before experimentation. Spectra of the gastrocnemius muscle were taken at rest and during stimulation of the sciatic nerve at 2 Hz for 10 min. Relative concentrations of intracellular phosphate (Pi), phosphocreatine (PCr) and ATP were determined. Iron deficiency increased PCr breakdown and production of acid in stimulated skeletal muscle. Recovery of PCr and Pi concentrations after exercise was slow. These metabolic changes are consistent with either a reduction in supply of oxygen to the muscle cell or altered oxidative phosphorylation by the mitochondria. The latter may be mediated by defective function of iron-containing proteins crucial in oxidative phosphorylation and this is suggested both by the observation that treatment with iron, sufficient to correct the anaemia, does not completely reverse the metabolic changes and that there is a different time course for such metabolic improvements and the observed increase in haemoglobin concentration.
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Affiliation(s)
- C H Thompson
- Medical Research Council Biochemical and Clinical Magnetic Resonance Unit, John Radcliffe Hospital, Oxford, United Kingdom
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13
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Abstract
Iron deficiency causes different abnormalities in the three major population groups that are at risk. In pregnant women, epidemiological studies suggest that anaemia, presumably due mainly to iron deficiency, is associated with an increased risk of low birth weight, prematurity, and perinatal mortality. In iron-deficient infants and children, there is convincing evidence of impaired psychomotor development and cognitive performance. Finally, iron-deficient women during the childbearing years (and iron-deficient men) have a decreased work capacity and less efficient response to exercise. These symptoms provide ample justification for preventing and treating a common and easily correctable nutritional disorder.
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MESH Headings
- Anemia, Hypochromic/blood
- Anemia, Hypochromic/complications
- Anemia, Hypochromic/drug therapy
- Child
- Child, Preschool
- Cognition Disorders/blood
- Cognition Disorders/etiology
- Embryonic and Fetal Development
- Exercise
- Female
- Humans
- Infant
- Infant, Low Birth Weight/blood
- Infant, Newborn
- Infant, Premature
- Infant, Premature, Diseases/etiology
- Iron/administration & dosage
- Iron/blood
- Iron Deficiencies
- Male
- Physical Fitness
- Pregnancy
- Pregnancy Complications, Hematologic/blood
- Pregnancy Complications, Hematologic/drug therapy
- Psychomotor Disorders/blood
- Psychomotor Disorders/etiology
- Task Performance and Analysis
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Affiliation(s)
- P R Dallman
- Department of Pediatrics, School of Medicine, University of California-San Francisco 94143
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