scholarly journals The significance of transferrin for intestinal iron absorption

Blood ◽  
1983 ◽  
Vol 61 (2) ◽  
pp. 283-290 ◽  
Author(s):  
HA Huebers ◽  
E Huebers ◽  
E Csiba ◽  
W Rummel ◽  
CA Finch
Keyword(s):  
Iron Absorption ◽  
Iron Status ◽  
Blood Stream ◽  
Intestinal Lumen ◽  
Jejunal Mucosa ◽  
Mean Values ◽  
Iron Deficient ◽  
Mucosal Cells ◽  
Recipient Animal ◽  
Diferric Transferrin

Abstract A mechanism is proposed by which apotransferrin is secreted from mucosal cells, loaded with iron in the intestinal lumen, and then the intact complex is taken into the cell. Within the cell, iron is released and transferred to the blood stream, whereas iron-free transferrin returns to the brush border to be recycled. We have investigated this hypothesis by measuring intestinal absorption of radioiron and 125I-labeled plasma transferrin using tied-off gut segments in normal and iron-deficient rats. There was no absorption of diferric transferrin from the ileum, but high absorption from the duodenum and jejunum segments. Jejunal absorption occurred as a function of the dose offered and showed saturation kinetics. In normal animals, 4 micrograms of the 50 micrograms of transferrin iron was absorbed over 1 hr. In iron-deficient animals, mean values as high as 13 micrograms were observed. Radioiron content of the jejunal mucosa bore a linear relationship to the dose administered and was inversely proportional to the amount of iron entering the plasma. Recycling of transferrin was indicated by the presence of labeled apotransferrin in the lumen, first observed between 15 and 60 min after the injection of diferric transferrin. A high resistance of diferric and apotransferrin to proteolytic degradation within the gut lumen was demonstrated. Comparative studies with lactoferrin and ferritin disclosed poor availability of their iron for absorption. The small amount that was absorbed did not relate to the iron status of the recipient animal. These studies support the role of mucosal transferrin as a shuttle protein for iron absorption.

scholarly journals The significance of transferrin for intestinal iron absorption

Blood ◽  
1983 ◽  
Vol 61 (2) ◽  
pp. 283-290
Author(s):  
HA Huebers ◽  
E Huebers ◽  
E Csiba ◽  
W Rummel ◽  
CA Finch
Keyword(s):  
Iron Absorption ◽  
Iron Status ◽  
Blood Stream ◽  
Intestinal Lumen ◽  
Jejunal Mucosa ◽  
Mean Values ◽  
Iron Deficient ◽  
Mucosal Cells ◽  
Recipient Animal ◽  
Diferric Transferrin

A mechanism is proposed by which apotransferrin is secreted from mucosal cells, loaded with iron in the intestinal lumen, and then the intact complex is taken into the cell. Within the cell, iron is released and transferred to the blood stream, whereas iron-free transferrin returns to the brush border to be recycled. We have investigated this hypothesis by measuring intestinal absorption of radioiron and 125I-labeled plasma transferrin using tied-off gut segments in normal and iron-deficient rats. There was no absorption of diferric transferrin from the ileum, but high absorption from the duodenum and jejunum segments. Jejunal absorption occurred as a function of the dose offered and showed saturation kinetics. In normal animals, 4 micrograms of the 50 micrograms of transferrin iron was absorbed over 1 hr. In iron-deficient animals, mean values as high as 13 micrograms were observed. Radioiron content of the jejunal mucosa bore a linear relationship to the dose administered and was inversely proportional to the amount of iron entering the plasma. Recycling of transferrin was indicated by the presence of labeled apotransferrin in the lumen, first observed between 15 and 60 min after the injection of diferric transferrin. A high resistance of diferric and apotransferrin to proteolytic degradation within the gut lumen was demonstrated. Comparative studies with lactoferrin and ferritin disclosed poor availability of their iron for absorption. The small amount that was absorbed did not relate to the iron status of the recipient animal. These studies support the role of mucosal transferrin as a shuttle protein for iron absorption.

Pharmacokinetics of pulmonary manganese absorption: evidence for increased susceptibility to manganese loading in iron-deficient rats

2005 ◽  
Vol 288 (5) ◽  
pp. L887-L893 ◽  
Author(s):  
Elizabeth Heilig ◽  
Ramon Molina ◽  
Thomas Donaghey ◽  
Joseph D. Brain ◽  
Marianne Wessling-Resnick
Keyword(s):  
Iron Deficiency ◽  
Iron Absorption ◽  
Iron Status ◽  
Mrna Levels ◽  
Blood Clearance ◽  
Divalent Metal Transporter 1 ◽  
Divalent Metal Transporter ◽  
Pulmonary Uptake ◽  
Iron Deficient ◽  
Metal Absorption

High levels of airborne manganese can be neurotoxic, yet little is known about absorption of this metal via the lungs. Intestinal manganese uptake is upregulated by iron deficiency and is thought to be mediated by divalent metal transporter 1 (DMT1), an iron-regulated factor known to play a role in dietary iron absorption. To better characterize metal absorption from the lungs to the blood and test whether iron deficiency may modify this process, the pharmacokinetics of pulmonary manganese and iron absorption by control and iron-deficient rats were compared. Levels of DMT1 expression in the lungs were determined to explore potential changes induced by iron deficiency that might alter metal absorption. The pharmacokinetic curves for intratracheally instilled54Mn and59Fe were significantly different, suggesting that pulmonary uptake of the two metals involves different mechanisms. Intratracheally instilled iron-deficient rats had significantly higher blood54Mn levels, whereas blood59Fe levels were significantly reduced compared with controls. The same trend was observed when radioisotopes were delivered by intravenous injection, indicating that iron-deficient rats have altered blood clearance of manganese. In situ analysis revealed the presence of DMT1 transcripts in airway epithelium; however, mRNA levels did not change in iron deficiency. Although lung DMT1 levels and metal absorption did not appear to be influenced by iron deficiency, the differences in blood clearance of instilled manganese identified by this study support the idea that iron status can influence the potential toxicity of this metal.

scholarly journals Resistance exercise improves the iron status without increasing the iron absorption in iron‐deficient rats (907.1)

2014 ◽  
Vol 28 (S1) ◽  
Author(s):  
Takako Fujii ◽  
Ayumi Nakashima ◽  
Chihiro Tanaka ◽  
Tatsuhiro Matsuo ◽  
Koji Okamura
Keyword(s):  
Resistance Exercise ◽  
Iron Absorption ◽  
Iron Status ◽  
Iron Deficient

scholarly journals Iron deficiency in Europe

2001 ◽  
Vol 4 (2b) ◽  
pp. 537-545 ◽  
Author(s):  
Serge Hercberg ◽  
Paul Preziosi ◽  
Pilar Galan
Keyword(s):  
Iron Deficiency ◽  
Iron Absorption ◽  
Blood Donation ◽  
Iron Status ◽  
Dietary Factors ◽  
Iron Nutrition ◽  
Dietary Recommendations ◽  
Iron Stores ◽  
Iron Deficient ◽  
Menstruating Women

AbstractIn Europe, iron deficiency is considered to be one of the main nutritional deficiency disorders affecting large fractions of the population, particularly such physiological groups as children, menstruating women and pregnant women. Some factors such as type of contraception in women, blood donation or minor pathological blood loss (haemorrhoids, gynaecological bleeding,..) considerably increase the difficulty of covering iron needs. Moreover, women, especially adolescents consuming lowenergy diets, vegetarians and vegans are at high risk of iron deficiency.Although there is no evidence that an anbsence of iron stores has any adverse consequences, it does indicate that iron nutrition is borderline, since any further reduction in body iron is associated with a decrease in the level of functional compounds such as haemoglobin.The prevalence of iron-deficient anaemia has slightly decreased in infants and menstruating women. Some positive factors may have contributed to reducing the prevalence of iron-deficiency anaemia in some groups of population: the use of iron-frotified formulas and iron-fortified cereals; the use of oral contraceptives and increased enrichment of iron in several countries; and the use of iron supplements during pregnancy in some European countries.It is possible to prevent and control iron deficiency by counseling individuals and families about sound iron nutrition during infancy and beyond, and about iron supplementation during pregnancy, by screening persons on the basis of their risk for iron deficiency, and by treating and following up persons with presumptive iron deficiency. This may help to reduce manifestations of iron deficiency and thus improve public health. Evidence linking iron status with risk of cardiovascular disease or cancer is unconvincing and does not justify changes in food fortification or medical practice, particularly because the benefits of assuring adequate iron intake during growth and development are well established. But stronger evidence is needed before rejecting the hypothesis that greater iron stores increase the incidence of CVD or cancer. At present, currently available data do not support radical changes in dietary recommendations. They include all means for increasing the content of dietary factors enhancing iron absorption or reducing the content of factors inhibiting iron absorption. Increased knowledge and increased information about factors may be important tools in the prevention of iron deficiency in Europe.

scholarly journals Olfactory ferric and ferrous iron absorption in iron-deficient rats

2012 ◽  
Vol 302 (12) ◽  
pp. L1280-L1286 ◽  
Author(s):  
V. M. Ruvin Kumara ◽  
Marianne Wessling-Resnick
Keyword(s):  
Nasal Cavity ◽  
Ferrous Iron ◽  
Iron Uptake ◽  
Ferric Iron ◽  
Iron Absorption ◽  
Iron Status ◽  
Occupational Exposures ◽  
Divalent Metal Transporter 1 ◽  
Divalent Metal Transporter ◽  
Iron Deficient

The absorption of metals from the nasal cavity to the blood and the brain initiates an important route of occupational exposures leading to health risks. Divalent metal transporter-1 (DMT1) plays a significant role in the absorption of intranasally instilled manganese, but whether iron uptake would be mediated by the same pathway is unknown. In iron-deficient rats, blood 59Fe levels after intranasal administration of the radioisotope in the ferrous form were significantly higher than those observed for iron-sufficient control rats. Similar results were obtained when ferric iron was instilled intranasally, and blood levels of 59Fe were even greater in the iron-deficient rats compared with the amount of ferrous iron absorbed. Experiments with Belgrade ( b/b) rats showed that DMT1 deficiency limited ferric iron uptake from the nasal cavity to the blood compared with +/b controls matched for iron deficiency. These results indicate that olfactory uptake of ferric iron by iron-deficient rats involves DMT1. Western blot experiments confirmed that DMT1 levels are significantly higher in iron-deficient rats compared with iron-sufficient controls in olfactory tissue. Thus the molecular mechanism of olfactory iron absorption is regulated by body iron status and involves DMT1.

Effect of hepcidin on intestinal iron absorption in mice

Blood ◽  
2004 ◽  
Vol 103 (10) ◽  
pp. 3940-3944 ◽  
Author(s):  
Abas H. Laftah ◽  
Bala Ramesh ◽  
Robert J. Simpson ◽  
Nita Solanky ◽  
Seiamak Bahram ◽  
...  
Keyword(s):  
Iron Uptake ◽  
Iron Absorption ◽  
Iron Status ◽  
Hfe Gene ◽  
Chain Reaction ◽  
Liver Iron ◽  
Hepcidin Expression ◽  
Iron Deficient ◽  
Polymerase Chain

Abstract The effect of the putative iron regulatory peptide hepcidin on iron absorption was investigated in mice. Hepcidin peptide was synthesized and injected into mice for up to 3 days, and in vivo iron absorption was measured with tied-off segments of duodenum. Liver hepcidin expression was measured by reverse transcriptase–polymerase chain reaction. Hepcidin significantly reduced mucosal iron uptake and transfer to the carcass at doses of at least 10 μg/mouse per day, the reduction in transfer to the carcass being proportional to the reduction in iron uptake. Synthetic hepcidin injections down-regulated endogenous liver hepcidin expression excluding the possibility that synthetic hepcidin was functioning by a secondary induction of endogenous hepcidin. The effect of hepcidin was significant at least 24 hours after injection of hepcidin. Liver iron stores and hemoglobin levels were unaffected by hepcidin injection. Similar effects of hepcidin on iron absorption were seen in iron-deficient and Hfe knockout mice. Hepcidin inhibited the uptake step of duodenal iron absorption but did not affect the proportion of iron transferred to the circulation. The effect was independent of iron status of mice and did not require Hfe gene product. The data support a key role for hepcidin in the regulation of intestinal iron uptake.

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