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Query: UMLS:C0240066 (iron deficiency)
 7,156 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to examine the effects of mild iron deficiency on physical work capacity, 40 prelatent iron-deficient female endurance runners were studied before and after 8 wk of supplementation with either oral iron (320 mg ferrous sulfate) or a matching placebo. Subjects underwent the following physical work capacity tests: the Wingate cycle ergometer test, the anaerobic speed test, the ventilatory threshold, VO2max, and maximal treadmill velocity during the VO2max test. Muscle biopsy samples pre- and post-treatment were obtained from 17 of the subjects, and these were assayed for citrate synthase and cytoplasmic alpha-glycerophosphate dehydrogenase activity. Subjects were randomly assigned to one of the treatment groups, and a double-blind method of administration of the supplements was used. The differences in improvement scores between the two groups on the work capacity and enzyme activity variables were statistically nonsignificant (P greater than 0.05). Serum ferritin values rose from a mean of 12.4 +/- 4.5 to 37.7 +/- 19.7 ng.ml-1 for the experimental group and from 12.2 +/- 4.3 to 17.2 +/- 8.9 ng.ml-1 for the controls (P = 0.0025), whereas hemoglobin levels remained fairly constant for both groups (P = 0.6). Eight weeks of iron supplementation to prelatent/latent iron-deficient, physically active females did not significantly enhance work capacity. Within the limitations of this study, the presence of a serum ferritin below 20 ng.ml-1 does not pose a significant handicap to physical work capacity.
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PMID:The effects of prelatent/latent iron deficiency on physical work capacity. 273 74

The purpose of this study was to determine whether severe iron deficiency alters the adaptive response of skeletal muscle fibers to a sustained increase in tonic contractile activity. Seven weanling rabbits consumed a low iron diet and underwent phlebotomy twice weekly for 6 mo, resulting in severe anemia (mean Hb 5.5 g/dl). Compared with control animals, tibialis anterior skeletal muscles of iron-deficient animals exhibited reduced concentrations of cytochrome c (4.4 +/- 0.7 vs. 8.6 +/- 0.7 nmol/g tissue; P less than 0.01), and reduced activities of citrate synthase (83 +/- 10 vs. 133 +/- 13 mU/mg protein; P less than 0.01) and cytochrome-c oxidase (2.2 +/- 0.2 vs. 3.6 +/- 0.5 U/mg protein; P less than 0.05). In these muscles mitochondria were swollen and displayed deformed cristae. Less severe biochemical abnormalities were observed in cardiac and soleus skeletal muscles. Ten days of continuous electrical stimulation of the motor nerve supplying anterior compartment muscles of iron-deficient rabbits increased expression of mitochondrial proteins: cytochrome c was increased to 154% of control levels (P less than 0.05), and cytochrome-c oxidase and citrate synthase activities were increased to 199 and 272% of control levels, respectively (P less than 0.005). In addition, electrical pacing increased the fractional volume of mitochondria observed by electron microscopy and reduced the activity of aldolase A by 28% (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Activity-induced adaptations in skeletal muscles of iron-deficient rabbits. 284 18

It has been reported that the mitochondrial cytochromes and citrate cycle enzymes occur in constant proportions to each other and increase or decrease roughly in parallel in response to various stimuli. The purpose of this study was to determine whether this proportionality is an obligatory consequence of the way in which mitochondria are assembled. Severe iron deficiency was used to bring about decreases of the iron-containing constituents of the mitochondrial respiratory chain in skeletal muscle. Cytochrome c concentration and cytochrome oxidase activity were decreased approximately 50%, while succinate dehydrogenase and NADH dehydrogenase activities were decreased by 78% in iron-deficient muscle. On electron microscopic examination, mitochondria in iron-deficient muscles had relatively sparse numbers of cristae. The iron deficiency had little or no effect on the levels of a range of mitochondrial matrix enzymes, including citrate synthase, isocitrate dehydrogenase, fumarase, aspartate aminotransferase, 3-hydroxyacyl-CoA dehydrogenase, 3-ketoacid-CoA transferase, and acetoacetyl-CoA thiolase. These results show that the usual constant proportions between the constituents of the mitochondrial respiratory chain and matrix enzymes are not obligatory; they provide evidence that mitochondrial matrix enzymes and respiratory chain constituents can be incorporated into mitochondria independently and that the ratios between them can vary within wide limits.
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PMID:Perturbation of mitochondrial composition in muscle by iron deficiency. Implications regarding regulation of mitochondrial assembly. 302 53

Young rats maintained on an iron-deficient diet developed severe anemia and had large decreases in the levels of the iron-containing flavoproteins and cytochromes of the mitochondrial respiratory chain in skeletal muscle. In contrast, the levels of a number of mitochondrial matrix marker enzymes, including citrate synthase, isocitrate dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase, 3-ketoacid-CoA transferase, and aspartate aminotransferase, increased in red skeletal muscle but not in white muscle. Phosphocreatine concentration was decreased and inorganic phosphate concentration was increased in soleus muscle frozen in situ. We hypothesize that the increase in mitochondrial matrix enzymes reflects a stimulus to mitochondrial biogenesis in posture-maintaining and weight-bearing red muscle fibers in severely iron-deficient rats. It is our working hypothesis that this stimulus to mitochondrial biogenesis arises from mild activity of the red fibers and is due to the same perturbation in cellular homeostasis that is normally caused by vigorous exercise or hypoxia. In iron deficiency, the stimulus to mitochondrial biogenesis can induce an increase in only those enzymes not prevented from increasing by iron deficiency, resulting in formation of mitochondria of grossly abnormal composition.
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PMID:Induction of an increase in mitochondrial matrix enzymes in muscle of iron-deficient rats. 347 8

The effects of chronic iron deficiency anemia on brain (cortex) metabolism were estimated by 31P-nuclear magnetic resonance spectroscopy and biochemical analyses in male Wistar rats. Iron deficiency anemia was induced by supplying diet containing either approximately 2 or approximately 6 ppm Fe. Control diet was supplemented with 100 ppm Fe as ferric citrate. After 8-9 weeks, blood hemoglobin levels were approximately 13, 5, and 3 g/100 ml in the 100 ppm, 6 ppm, and 2 ppm Fe group, respectively. The blood lactate levels at rest in these groups were approximately 3, 5, and 6 mM. The blood glucose concentration also tended to be elevated in iron-deficient rats. The high-energy phosphate contents in brain were not affected by iron deficiency. The activities of succinate dehydrogenase and cytochrome oxidase per unit protein in the 2 ppm Fe group were significantly less than in the 100 ppm Fe group, but those activities were not significantly affected by feeding diet with 6 ppm Fe. The activities of lactate dehydrogenase in iron-deficient group tended to be elevated but not significantly. The activities of non-iron containing mitochondrial enzymes, citrate synthase and beta-hydroxyacyl CoA dehydrogenase, were unchanged. It is suggested that the brain has a higher tolerance to iron deficiency than skeletal muscle in terms of the metabolic characteristics, although this may be associated with a lower level of neural activity.
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PMID:Effects of chronic iron deficiency anemia on brain metabolism. 756 62

The effects of iron deficiency and iron resupply on the metabolism of leaf organic acids have been investigated in hydroponically grown sugar beet. Organic acid concentrations and activities in leaf extracts of several enzymes related to organic acid metabolism were measured. Enzymes assayed included phosphoenol pyruvate carboxylase (PEPC; EC 4.1.1.31), different Krebs cycle enzymes: malate dehydrogenase (MDH; EC 1.1.1.37), aconitase (EC 4.2.1.3), fumarase (EC 4.2.1.2), citrate synthase (CS; EC 4.1.3.7) and isocitrate dehydrogenase (ICDH; EC 1.1.1.42), glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and two enzymes related to anaerobic metabolism (lactate dehydrogenase [LDH]; EC 1.1.1.27, and pyruvate decarboxylase [PDC]; EC 4.1.1.1). Iron concentration in leaves was severely decreased by iron deficiency. Iron resupply caused an increase in iron concentrations, reaching levels similar to the controls in 96 h. Iron deficiency induced a 2.3-fold (from 16 to 37 mmol m-2) increase in leaf total organic acid concentration. Organic anion concentrations were still 4-fold higher than the controls 24 h after resupply and decreased to values similar to those found in the controls after 96 h. All measured enzymes had increased activities in extracts of iron-deficient leaves when compared to the controls and generally decreased to control values 24 h after iron addition. These data provide evidence that organic acid accumulation in iron-deficient leaves is likely not due to an enhancement in leaf carbon fixation. Instead, this accumulation could be associated with organic acid export from the roots to the leaves via xylem.
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PMID:Changes induced by Fe deficiency and Fe resupply in the organic acid metabolism of sugar beet (Beta vulgaris) leaves. 1131 12

X-linked sideroblastic anemia with ataxia (XLSA/A) is caused by defects of the transporter ABCB7 and is characterized by mitochondrial iron deposition and excess of protoporphyrin in erythroid cells. We describe ABCB7 silencing in HeLa cells by performing sequential transfections with siRNAs. The phenotype of the ABCB7-deficient cells was characterized by a strong reduction in proliferation rate that was not rescued by iron supplementation, by evident signs of iron deficiency, and by a large approximately 6-fold increase of iron accumulation in the mitochondria that was poorly available to mitochondrial ferritin. The cells showed an increase of protoporphyrin IX, a higher sensitivity to H(2)O(2) toxicity, and a reduced activity of mitochondrial superoxide dismutase 2 (SOD2), while the activity of mitochondrial enzymes, such as citrate synthase or succinate dehydrogenase, and ATP content were not decreased. In contrast, aconitase activity, particularly that of the cytosolic, IRP1 form, was reduced. The results support the hypothesis that ABCB7 is involved in the transfer of iron from mitochondria to cytosol, and in the maturation of cytosolic Fe/S enzymes. In addition, the results indicate that anemia in XLSA/A is caused by the accumulation of iron in a form that is not readily usable for heme synthesis.
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PMID:RNA silencing of the mitochondrial ABCB7 transporter in HeLa cells causes an iron-deficient phenotype with mitochondrial iron overload. 1719 93

Iron deficiency anemia indicates poor nutrition and is a public health problem. Iron deficiency is also associated with muscle weakness. However, the intracellular mechanisms by which iron deficiency induces muscle weakness are obscure. The purpose of the present study was to evaluate the effect of iron deficiency on protein synthesis in basal and branched-amino acids (BCAA)- and insulin-stimulated state in muscle cells. Differentiated C2C12 myotubes were incubated with an iron chelator, deferoxamine mesylate, and then stimulated with BCAA or insulin to activate protein synthesis. This iron deprivation resulted in a significant reduction in the abundance of iron-containing proteins, such as the mitochondrial complex 1 subunit protein, compared to control cells, but not of protein that does not contain iron, such as citrate synthase. Proteins involved in glucose utilization, such as glucose transpoter-1, hexokinase and AMP-activated protein kinase (AMPK), were upregulated under iron deficiency. Additionally, rates of BCAA- and insulin-stimulated protein synthesis, measured by puromycin incorporation, were lower in iron-deficient myotubes than in control cells. We suggest that low iron availability attenuates BCAA- and insulin-stimulated protein synthesis, possibly via activation of AMPK in myotubes. The present findings advance the understanding of the importance of iron to skeletal muscle protein synthesis and, thus, may contribute to the prevention of sarcopenia and frailty.
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PMID:Iron deficiency attenuates protein synthesis stimulated by branched-chain amino acids and insulin in myotubes. 3278 44