| Membrane potential dependence of Fe(III) uptake by mouse duodenum. | |
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MedLine Citation:
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PMID: 2775776 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Intestinal iron uptake by mouse duodenal fragments is inhibited in the absence of oxygen and glucose from the incubation medium and by a variety of metabolic inhibitors. The mechanism of energy coupling to iron uptake is, however, unclear. In vitro experiments using duodenal fragments showed Fe3+ uptake to be markedly inhibited, in a reversible fashion, by the replacement of incubation medium Na+ by K+. Addition of phloridzin to the medium failed to affect iron uptake, suggesting that the above effect was not a consequence of reduced glucose uptake. Substitution of Na+ by Rb+ also potently reduced duodenal iron uptake. Replacement of medium NaCl by either mannitol or choline chloride had no significant effect on Fe3+ uptake, thus excluding the possibility of the Fe3+ uptake process being Na+-dependent. Similar observations were made with duodenal fragments from animals with enhanced Fe3+ absorption, due to chronic hypoxia. Valinomycin (1-5 microM) increased the uptake of both glucose and Fe3+. Higher concentrations (22.5 microM) of the ionophore were inhibitory. In vivo studies (tied-off segments) using Rb+-containing medium confirmed the inhibitory effects of univalent cations on Fe3+ absorption. Enhanced absorption of Fe3+ was also demonstrable in vivo, with low concentrations of valinomycin and nigericin added to the luminal medium. These observations suggest that the Fe3+ uptake process may be dependent on the brush-border membrane potential. |
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Authors:
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K B Raja; R J Simpson; T J Peters |
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Publication Detail:
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Type: In Vitro; Journal Article |
Journal Detail:
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Title: Biochimica et biophysica acta Volume: 984 ISSN: 0006-3002 ISO Abbreviation: Biochim. Biophys. Acta Publication Date: 1989 Sep |
Date Detail:
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Created Date: 1989-10-13 Completed Date: 1989-10-13 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0217513 Medline TA: Biochim Biophys Acta Country: NETHERLANDS |
Other Details:
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Languages: eng Pagination: 262-6 Citation Subset: IM |
Affiliation:
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Department of Clinical Biochemistry, King's College School of Medicine and Dentistry, London, U.K. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Biological Transport, Active Cations, Monovalent / pharmacology Duodenum / physiology* Ferric Compounds / metabolism* Glucose / metabolism Intestinal Absorption / drug effects Intestinal Mucosa / physiology* Membrane Potentials Mice Nigericin / pharmacology Oxygen / physiology Valinomycin / pharmacology |
| Chemical | |
Reg. No./Substance:
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0/Cations, Monovalent; 0/Ferric Compounds; 2001-95-8/Valinomycin; 28380-24-7/Nigericin; 50-99-7/Glucose; 7782-44-7/Oxygen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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