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“Ferrocrinology”—Iron Is an Important Factor Involved in Gluco- and Lipocrinology. Nutrients 2022; 14:nu14214693. [DOI: 10.3390/nu14214693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/04/2022] [Accepted: 11/04/2022] [Indexed: 11/09/2022] Open
Abstract
“Ferrocrinology” is the term used to describe the study of iron effects on the functioning of adipose tissue, which together with muscle tissue makes the largest endocrine organ in the human body. By impairing exercise capacity, reducing AMP-activated kinase activity, and enhancing insulin resistance, iron deficiency can lead to the development of obesity and type 2 diabetes mellitus. Due to impaired browning of white adipose tissue and reduced mitochondrial iron content in adipocytes, iron deficiency (ID) can cause dysfunction of brown adipose tissue. By reducing ketogenesis, aconitase activity, and total mitochondrial capacity, ID impairs muscle performance. Another important aspect is the effect of ID on the impairment of thermogenesis due to reduced binding of thyroid hormones to their nuclear receptors, with subsequently impaired utilization of norepinephrine in tissues, and impaired synthesis and distribution of cortisol, which all make the body’s reactivity to stress in ID more pronounced. Iron deficiency can lead to the development of the most common endocrinopathy, autoimmune thyroid disease. In this paper, we have discussed the role of iron in the cross-talk between glucocrinology, lipocrinology and myocrinology, with thyroid hormones acting as an active bystander.
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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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Stugiewicz M, Tkaczyszyn M, Kasztura M, Banasiak W, Ponikowski P, Jankowska EA. The influence of iron deficiency on the functioning of skeletal muscles: experimental evidence and clinical implications. Eur J Heart Fail 2016; 18:762-73. [PMID: 26800032 DOI: 10.1002/ejhf.467] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/16/2015] [Accepted: 10/22/2015] [Indexed: 12/26/2022] Open
Abstract
Skeletal and respiratory myopathy not only constitutes an important pathophysiological feature of heart failure and chronic obstructive pulmonary disease, but also contributes to debilitating symptomatology and predicts worse outcomes in these patients. Accumulated evidence from laboratory experiments, animal models, and interventional studies in sports medicine suggests that undisturbed systemic iron homeostasis significantly contributes to the effective functioning of skeletal muscles. In this review, we discuss the role of iron status for the functioning of skeletal muscle tissue, and highlight iron deficiency as an emerging therapeutic target in chronic diseases accompanied by a marked muscle dysfunction.
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Affiliation(s)
- Magdalena Stugiewicz
- Students' Scientific Association, Laboratory for Applied Research on Cardiovascular System, Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
| | - Michał Tkaczyszyn
- Laboratory for Applied Research on Cardiovascular System, Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland.,Cardiology Department, Centre for Heart Diseases, Military Hospital, Wroclaw, Poland
| | - Monika Kasztura
- Laboratory for Applied Research on Cardiovascular System, Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
| | - Waldemar Banasiak
- Cardiology Department, Centre for Heart Diseases, Military Hospital, Wroclaw, Poland
| | - Piotr Ponikowski
- Cardiology Department, Centre for Heart Diseases, Military Hospital, Wroclaw, Poland.,Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
| | - Ewa A Jankowska
- Laboratory for Applied Research on Cardiovascular System, Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland.,Cardiology Department, Centre for Heart Diseases, Military Hospital, Wroclaw, Poland
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Abstract
Iron is a trace mineral that is highly significant to endurance athletes. Iron is critical to optimal athletic performance because of its role in energy metabolism, oxygen transport, and acid-base balance. Endurance athletes are at increased risk for suboptimal iron status, with potential negative consequences on performance, because of the combination of increased iron needs and inadequate dietary intake. This review paper summarizes the role of iron in maximal and submaximal exercise and describes the effects of iron deficiency on exercise performance. Mechanisms that explain the increased risk of iron deficiency in endurance athletes, including exercise-associated inflammation and hepcidin release on iron sequestration, are described. Information on screening athletes for iron deficiency is presented, and suggestions to increase iron intake through diet modification or supplemental iron are provided.
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Affiliation(s)
- Pamela S Hinton
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO 65211, USA
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McCann JC, Ames BN. An overview of evidence for a causal relation between iron deficiency during development and deficits in cognitive or behavioral function. Am J Clin Nutr 2007; 85:931-45. [PMID: 17413089 DOI: 10.1093/ajcn/85.4.931] [Citation(s) in RCA: 261] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
This review, intended for a broad scientific readership, summarizes evidence relevant to whether a causal relation exists between dietary iron deficiency with (ID+A) or without (ID-A) anemia during development and deficits in subsequent cognitive or behavioral performance. An overview of expert opinion and major evidence in humans and animals is provided. Cognitive and behavioral effects observed in humans with ID-A and in animals with ID+/-A are provided in tables. The degree to which 5 conditions of causality are satisfied and whether deleterious effects of ID-A might be expected to occur are discussed. On the basis of the existing literature, our major conclusions are as follows. Although most of the 5 conditions of causality (association, plausible biological mechanisms, dose response, ability to manipulate the effect, and specificity of cause and effect) are partially satisfied in humans, animals, or both, a causal connection has not been clearly established. In animals, deficits in motor activity are consistently associated with severe ID+A, but adverse effects on performance in tests that target cognitive function have not been clearly shown. Resistance to iron treatment was observed in most trials of children <2 y of age with ID+A, but not in older children. Similar observations were made in rodents when ID+A occurred before rather than after weaning. In children >2 y of age and in adolescents with ID-A, evidence suggests cognitive or behavioral deficits; however, the surprisingly small number of studies conducted in either humans or animals prevents a thorough assessment.
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Affiliation(s)
- Joyce C McCann
- Nutrition and Metabolism Center, Children's Hospital Oakland Research Institute, Oakland, CA, USA.
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Shiga K, Hara H, Okano G, Aoyama Y. Ingestion of water-soluble soybean fiber prevents gastrectomy-induced iron malabsorption, anemia and impairment of voluntary running exercise performance in rats. J Nutr 2003; 133:1120-6. [PMID: 12672929 DOI: 10.1093/jn/133.4.1120] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber, on gastrectomy-induced iron malabsorption, anemia and impairment of exercise performance in rats in two separate experiments. The study was designed as a 2 x 2 factorial arrangement with operation (total gastrectomy) and diet (WSSF) under sedentary (Experiment 1) and exercised (Experiment 2) conditions. In Experiment 1, gastrectomy reduced net iron absorption, hemoglobin concentration, hematocrit and hemoglobin regeneration efficiency (P < 0.01). However, in rats fed a WSSF diet (50 g/kg diet), iron absorption and the hematological variables of the gastrectomized rats were comparable to those in the sham-operated rats, demonstrating that ingestion of WSSF promotes iron absorption and prevents anemia after gastrectomy. Feeding WSSF increased pools of organic acids and soluble iron in cecal contents and decreased the pH of the cecal contents (P < 0.001). Of the many cecal variables measured, net iron absorption in gastrectomized rats was most closely correlated (r = 0.614, P < 0.01) with the short-chain fatty acid pool in the cecum. Cecal fermentation of WSSF may contribute to improvements in gastrectomy-induced nutritional defects. In Experiment 2, we examined voluntary running exercise performance in totally gastrectomized rats fed diets with or without WSSF. Total gastrectomy severely impaired running performance (P < 0.001), and WSSF feeding largely restored the lowered performance. We conclude that feeding WSSF improves anemia and impaired voluntary running performance in totally gastrectomized rats.
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Affiliation(s)
- Kazuki Shiga
- Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
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Brutsaert TD, Hernandez-Cordero S, Rivera J, Viola T, Hughes G, Haas JD. Iron supplementation improves progressive fatigue resistance during dynamic knee extensor exercise in iron-depleted, nonanemic women. Am J Clin Nutr 2003; 77:441-8. [PMID: 12540406 DOI: 10.1093/ajcn/77.2.441] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Tissue iron depletion may negatively affect endurance performance and muscle fatigability. OBJECTIVE We investigated tissue-level iron depletion and progressive fatigue of the quadriceps during dynamic knee-extension exercise in young women. DESIGN Twenty iron-depleted (serum ferritin < 20 micro g/L), nonanemic (hemoglobin > 110 g/L) women (macro x +/- SEM age: 29.1 +/- 1.2 y) received iron (iron group) or placebo (placebo group) for 6 wk in a randomized, double-blind trial (n = 10 per group). A protocol integrating 2-3-s maximal voluntary static contractions (MVCs) with dynamic knee extensions was used to assess fatigue. RESULTS No significant differences between the groups in baseline iron status, MVC at rest, or MVC at the end of the protocol were observed. After treatment, serum iron and transferrin saturation increased significantly in the iron group (P = 0.02 and P = 0.03, respectively). Serum transferrin receptor concentrations increased significantly in the placebo group (P < 0.01) but not in the iron group. After treatment, the rate of decrease in MVC was attenuated in the iron group but not in the placebo group (P = 0.01). In the iron group, MVC at the sixth minute of the fatigue protocol and MVC at the end of the protocol were approximately 15% (P = 0.04) and approximately 27% higher (P < 0.01), respectively, after treatment. These improvements were not related to changes in iron-status indexes or tissue iron stores, although power was low (< 0.50) to detect these relations. CONCLUSIONS Iron supplementation was associated with a significant improvement in muscle fatigability. Interpretation regarding the direct role of tissue iron status is limited by the study's low power to detect relations between tissue iron improvement and decreased muscle fatigue.
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Affiliation(s)
- Tom D Brutsaert
- Department of Anthropology, the State University of New York at Albany, 12222, USA.
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Beard JL. Iron biology in immune function, muscle metabolism and neuronal functioning. J Nutr 2001; 131:568S-579S; discussion 580S. [PMID: 11160590 DOI: 10.1093/jn/131.2.568s] [Citation(s) in RCA: 593] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The estimated prevalence of iron deficiency in the world suggests that there should be widespread negative consequences of this nutrient deficiency in both developed and developing countries. In considering the reality of these estimates, the Belmont Conference seeks to reconsider the accepted relationships of iron status to physiological, biochemical and neurological outcomes. This review focuses on the biological processes that we believe are the basis for alterations in the immune system, neural systems, and energy metabolism and exercise. The strength of evidence is considered in each of the domains and the large gaps in knowledge of basic biology or iron-dependent processes are identified. Iron is both an essential nutrient and a potential toxicant to cells; it requires a highly sophisticated and complex set of regulatory approaches to meet the demands of cells as well as prevent excess accumulation. It is hoped that this review of the more basic aspects of the biology of iron will set the stage for subsequent in-depth reviews of the relationship of iron to morbidity, mortality and functioning of iron-deficient individuals and populations.
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Affiliation(s)
- J L Beard
- Nutrition Department, College of Human Development, The Pennsylvania State State University, University Park, PA 16802, USA
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Haas JD, Brownlie T. Iron deficiency and reduced work capacity: a critical review of the research to determine a causal relationship. J Nutr 2001; 131:676S-688S; discussion 688S-690S. [PMID: 11160598 DOI: 10.1093/jn/131.2.676s] [Citation(s) in RCA: 613] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The causal relationship between iron deficiency and physical work capacity is evaluated through a systematic review of the research literature, including animal and human studies. Iron deficiency was examined along a continuum from severe iron-deficiency anemia (SIDA) to moderate iron-deficiency anemia (MIDA) to iron deficiency without anemia (IDNA). Work capacity was assessed by aerobic capacity, endurance, energetic efficiency, voluntary activity and work productivity. The 29 research reports examined demonstrated a strong causal effect of SIDA and MIDA on aerobic capacity in animals and humans. The presumed mechanism for this effect is the reduced oxygen transport associated with anemia; tissue iron deficiency may also play a role through reduced cellular oxidative capacity. Endurance capacity was also compromised in SIDA and MIDA, but the strong mediating effects of poor cellular oxidative capacity observed in animals have not been demonstrated in humans. Energetic efficiency was affected at all levels of iron deficiency in humans, in the laboratory and the field. The reduced work productivity observed in field studies is likely due to anemia and reduced oxygen transport. The social and economic consequences of iron-deficiency anemia (IDA) and IDNA have yet to be elucidated. The biological mechanisms for the effect of IDA on work capacity are sufficiently strong to justify interventions to improve iron status as a means of enhancing human capital. This may also extend to the segment of the population experiencing IDNA in whom the effects on work capacity may be more subtle, but the number of individuals thus affected may be considerably more than those experiencing IDA.
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Affiliation(s)
- J D Haas
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853-6301, USA.
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10
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Abstract
The prevalence of iron deficiency anemia is likely to be higher in athletic populations and groups, especially in younger female athletes, than in healthy sedentary individuals. In anemic individuals, iron deficiency often not only decreases athletic performance but also impairs immune function and leads to other physiologic dysfunction. Although it is likely that dietary choices explain much of a negative iron balance, evidence also exists for increased rates of red cell iron and whole-body iron turnover. Other explanations of decreased absorption and increased sweat or urine losses are unlikely. The young female athlete may want to consider use of low-dose iron supplements under medical and dietary supervision to prevent a decline in iron status during training.
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Affiliation(s)
- J Beard
- Nutrition Department, Pennsylvania State University, University Park, PA 16802, USA. its.psu.edu
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Okura H, Inoue H, Tomon M, Nishiyama S, Yoshikawa T, Yoshida K, Yoshikawa J. Impact of Doppler-derived left ventricular diastolic performance on exercise capacity in normal individuals. Am Heart J 2000; 139:716-22. [PMID: 10740157 DOI: 10.1016/s0002-8703(00)90054-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Doppler-derived left ventricular (LV) diastolic indexes have been shown to correlate with exercise capacity in patients with heart diseases as well as healthy individuals. However, it is uncertain whether they predict exercise capacity independent of noncardiac factors. METHODS To clarify the impact of the LV diastolic index on exercise capacity, 160 healthy individuals were investigated. All underwent Bruce protocol treadmill stress testing and 2-dimensional and Doppler echocardiography. Estimated metabolic equivalent was calculated from exercise time (metabolic equivalent = 1.11 + 0.016 x exercise time). Diastolic performance was assessed by Doppler transmitral flow velocity pattern. Pulmonary function tests and complete blood cell count were also performed. RESULTS LV diastolic indexes correlated well with metabolic equivalent (peak transmitral filling velocity (A): r = -0.51, P <.0001; ratio of early and late transmitral filling velocities (E/A): r = 0.58, P <. 0001). However, there was no significant correlation between LV systolic indexes and metabolic equivalent. Independent predictors for a higher metabolic equivalent by multivariate analysis were higher E/A (P <.0001), higher vital capacity (P =.001), smaller body mass index (P =.0003), younger age (P =.0050), and higher hemoglobin concentration (P =.0026). CONCLUSION Doppler-derived LV diastolic index may help in predicting exercise capacity in normal individuals independent of other cardiac and extracardiac factors.
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Affiliation(s)
- H Okura
- Department of Internal Medicine, Kobe Rehabilitation Hospital, Japan.
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Abstract
Iron plays an important role, not only in oxygen delivery to the tissues, but also as a cofactor with several enzymes involved in energy metabolism and thermoregulation. As a result, much research has been dedicated to understanding the ramifications of iron depletion and iron deficiency anemia on the physiological functions of these enzymes. There is evidence to suggest that iron depletion and iron deficiency anemia cause physiological changes in the body not only during exercise, but also under resting conditions. Both rat and human studies have produced results revealing elevated levels of norepinephrine in the blood and urine of iron-deficient anemic subjects. These studies also provide evidence to suggest that elevation in metabolic rate may ultimately lead to slower growth rates and lower body weights in iron-deficient anemic animals and humans. The focus of this review is on the effects of iron deficiency on metabolic rate and thermoregulation. Prior to this discussion, a brief background on iron is presented.
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Affiliation(s)
- P H Rosenzweig
- University of Massachusetts, Department of Nutrition, Chenoweth Lab, Amherst 01003-1420, USA
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Paterson JA, Davis J, Gregory M, Holt SJ, Pachulski A, Stamford DE, Wothers JB, Jarrett A. A study on the effects of low haemoglobin on postnatal women. Midwifery 1994; 10:77-86. [PMID: 8057960 DOI: 10.1016/s0266-6138(05)80249-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE to assess the effect of low haemoglobin (Hb) on the mental and physical health of postnatal women. DESIGN survey conducted between May 1991 and February 1992. SETTING maternity unit in district general hospital in the UK. PARTICIPANTS 1010 postnatal women who had delivered a live baby, did not stay in hospital for seven or more days postnatally, whose baby was not admitted to the neonatal unit and who did not have a current psychiatric disorder. MEASUREMENTS Hb levels at 'booking', 34 weeks gestation, three days and six weeks post delivery; the Edinburgh Postnatal Depression Scale (EPDS) and a self-completion questionnaire at ten days, four weeks and six weeks post delivery. FINDINGS women with a low Hb are more likely to be under 25 years of age, primiparous, be anaemic at 34 weeks gestation, not to have had a normal delivery, have had a blood loss greater than 250 ml and to have had heavy lochia postnatally. Low Hb levels were not associated with high EPDS scores. Low Hb levels were related to reports of low energy, breathlessness, faintness/dizziness, painful perineal sutures and tingling in fingers and toes at ten days post delivery. Whilst tiredness persisted to six weeks post delivery the other symptoms disappeared. IMPLICATIONS FOR PRACTICE in order to reduce the incidence of postnatal anaemia a review of policies for testing is recommended so that the incidence of physical problems in the first six weeks can be reduced. There is a need for further research into the causes and potential alleviation of tiredness.
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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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Linderman JK, Dallman PR, Rodriguez RE, Brooks GA. Lactate is essential for maintenance of euglycemia in iron-deficient rats at rest and during exercise. THE AMERICAN JOURNAL OF PHYSIOLOGY 1993; 264:E662-7. [PMID: 8097376 DOI: 10.1152/ajpendo.1993.264.4.e662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
To evaluate the hypothesis that lactate supply is essential to maintain euglycemia during iron deficiency, female Sprague-Dawley rats were assigned to iron-sufficient (50 mg Fe2+/kg diet, +Fe), or iron-deficient (15 mg Fe2+/kg diet, -Fe) dietary groups and were injected with a specific beta 2-adrenergic inhibitor, ICI 118,551 (1.0 mg/kg body wt). Rats were studied at rest or after 30 min of running at 13.4 m/min 0% grade. Dietary iron deficiency decreased hemoglobin concentration 38%, but resting arterial concentrations of glucose ([Glc]), lactate ([La]), or alanine ([Ala]) were unaffected. Administration of ICI 118,551 (beta 2-blockade) decreased [La] and [Glc] 52 and 32% in resting -Fe rats, respectively. beta 2-Blockade attenuated the exercise-induced rise in [La] and decreased [Glc] 31% in exercising -Fe rats. [Ala] were unaffected by iron deficiency or exercise but decreased 24 and 18% because of beta 2-blockade in resting and exercising +Fe rats. Iron deficiency depleted resting liver glycogen concentration 45%, with no additional effect of exercise or beta 2-blockade. beta-Blockade decreased arterial insulin and increased arterial glucagon concentrations in resting -Fe and +Fe rats. During exercise glucagon concentration increased significantly more in -Fe than +Fe rats. Decreased arterial [La] with a corresponding decrease in arterial [Glc] in response to beta 2-blockade support the contention that lactate supply is critical to maintenance of euglycemia in -Fe rats at rest and during exercise.
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Affiliation(s)
- J K Linderman
- Department of Physical Education, University of California, Berkeley 94720
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Borel MJ, Beard JL, Farrell PA. Hepatic glucose production and insulin sensitivity and responsiveness in iron-deficient anemic rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1993; 264:E380-90. [PMID: 8460685 DOI: 10.1152/ajpendo.1993.264.3.e380] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We performed euglycemic hyperinsulinemic glucose clamps at insulin infusion rates of 1.9, 4.0, 9.3, and 19.3 mU.kg-1 x min-1 in rats with varying severities of iron deficiency anemia (IDA; mean hemoglobin concentrations of 59, 79, 107, and 137 g/l) to assess the effect of IDA on insulin sensitivity and responsiveness. Glucose appearance and disappearance (Rd) rates were determined using a primed continuous infusion of [3-3H]glucose. Basal plasma glucose and insulin concentrations were similar between the IDA and control rats. Basal hepatic glucose production was significantly (P = 0.0001) elevated in the two most anemic groups (13.6 +/- 2.4 and 12.6 +/- 3.1 vs. 10.6 +/- 2.2 and 10.2 +/- 2.0 mg.kg-1 x min-1). A significant upward shift in the insulin dose-response curves for Rd indicated an increase in peripheral insulin responsiveness in the two most anemic groups while a slight leftward shift was suggestive of an increase in insulin sensitivity in all three anemic groups. Hepatic insulin sensitivity and responsiveness were unaffected by IDA. We conclude that increased glucose utilization rates in IDA rats are due primarily to an increase in peripheral insulin responsiveness.
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Affiliation(s)
- M J Borel
- Nutrition Department, Pennsylvania State University, University Park 16802
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Brooks GA, Henderson SA, Dallman PR. Increased glucose dependence in resting, iron-deficient rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1987; 253:E461-6. [PMID: 3661703 DOI: 10.1152/ajpendo.1987.253.4.e461] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Rates of blood glucose and lactate turnover were assessed in resting iron-deficient and iron-sufficient (control) rats to test the hypothesis that dependence on glucose metabolism is increased in iron deficiency. Male Sprague-Dawley rats, 21 days old, were fed a diet containing either 6 mg iron/kg feed (iron-deficient group) or 50 mg iron/kg feed (iron-sufficient group) for 3-4 wk. The iron-deficient group became anemic, with hemoglobin levels of 6.4 +/- 0.2 compared with 13.8 +/- 0.3 g/dl for controls. Rats received a 90-min primed continuous infusion of D-[6-3H]glucose and sodium L-[U-14C]lactate via a jugular catheter. Serial samples were taken from a carotid catheter for concentration and specific activity determinations. Iron-deficient rats had significantly (P less than 0.05) higher blood glucose (7.1 +/- 0.3 vs. 6.1 +/- 0.2 mM) and lactate concentrations than controls (1.0 +/- 0.1 vs. 0.8 +/- 0.1 mM). The iron-deficient group had a significantly higher glucose turnover rate (67 +/- 2 vs. 58 +/- 4 mumol . kg-1 . min-1) than the control group. Significantly more metabolite recycling in iron-deficient rats was indicated by greater incorporation of 14C (from infused [14C]-lactate) into blood glucose. Assuming a carbon crossover correction factor of 2, half of blood glucose arose from lactate in deficient animals. By comparison, only 25% of glucose arose from lactate in controls. Lack of a difference in lactate turnover (irreversible disposal) rates between deficient rats and controls (191 +/- 26 vs. 163 +/- 15 mumol . kg-1 . min-1) was attributed to 14C recycling.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- G A Brooks
- Department of Physical Education, University of California, Berkeley 94720
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Perkkiö MV, Jansson LT, Henderson S, Refino C, Brooks GA, Dallman PR. Work performance in the iron-deficient rat: improved endurance with exercise training. THE AMERICAN JOURNAL OF PHYSIOLOGY 1985; 249:E306-11. [PMID: 2994490 DOI: 10.1152/ajpendo.1985.249.3.e306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effect of an endurance training regimen on muscle oxidative enzymes and work performance was studied in iron-deficient and -sufficient rats. Three-week-old male Sprague-Dawley rats (n = 40) were randomly assigned to diets containing either 6 mg iron/kg (iron deficient) or 50 mg iron/kg (iron sufficient). After 2 wk, each group of rats was further divided into untrained or endurance-trained subgroups. Training consisted of daily treadmill running of gradually increasing duration for a 1-mo period. After the training period, sedentary and endurance-trained iron-deficient rats were anemic (Hgb approximately 8 g/dl compared with 16 g/dl in the 2 control groups) and had significantly lower skeletal muscle cytochrome c concentration, cytochrome oxidase activity, and succinic oxidase activity compared with the iron-sufficient groups. In response to training iron-deficient rats also generally had a substantial increase in skeletal muscle oxidative enzymes (P less than 0.05), in contrast to iron-sufficient animals, in which there was little or no training effect. Work performance in response to training in the iron-deficient rats improved more than sixfold in an endurance type of exercise (P less than 0.05), but maximal oxygen consumption during a brief, intense type of exercise was not significantly affected. The results suggest that endurance training of iron-deficient rats results in a milder anemia and less drastic reduction of skeletal muscle oxidative enzymes which in turn allows better performance in an endurance type of exercise.
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