| H/dipeptide absorption across the human intestinal epithelium is controlled indirectly via a functional Na/H exchanger. | |
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MedLine Citation:
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PMID: 11984519 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND & AIMS: For optimal nutrient absorption to occur, the enterocyte must express a range of specialist ion-driven carrier proteins that function cooperatively in a linked and mutually dependent fashion. Thus, absorption via the human intestinal H(+)-coupled di/tripeptide transporter (hPepT1) is dependent on maintenance of the trans-apical driving force (the H(+)-electrochemical gradient) established, in part, by brush-border Na(+)/H(+) exchanger (NHE3) activity. This study aimed to examine whether physiologic regulation of NHE3 activity can limit hPepT1 capacity and, therefore, protein absorption after a meal. METHODS: hPepT1 and NHE3 activities were determined in intact human intestinal epithelial Caco-2 cell monolayers by measurements of [(14)C]glycylsarcosine transport and uptake, (22)Na(+)-influx, H(+)-influx, and H(+)-efflux. Expression of NHE regulatory factors was determined by reverse-transcriptase polymerase chain reaction. RESULTS: Optimal dipeptide transport was observed in the presence of a transapical pH gradient and extracellular Na(+). At apical pH 6.5, and only in Na(+)-containing media, protein kinase A activation (by forskolin or vasoactive intestinal peptide) or selective NHE3 inhibition (by S1611) reduced transepithelial dipeptide transport and cellular accumulation by a reduction in the capacity (without effect on affinity) of dipeptide uptake. CONCLUSIONS: Protein kinase A-mediated modulation of intestinal dipeptide absorption is indirect via effects on the apical Na(+)/H(+) exchanger. |
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Authors:
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David T Thwaites; David J Kennedy; Demetrio Raldua; Catriona M H Anderson; Maria E Mendoza; Catherine L Bladen; Nicholas L Simmons |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Gastroenterology Volume: 122 ISSN: 0016-5085 ISO Abbreviation: Gastroenterology Publication Date: 2002 May |
Date Detail:
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Created Date: 2002-05-01 Completed Date: 2002-05-23 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0374630 Medline TA: Gastroenterology Country: United States |
Other Details:
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Languages: eng Pagination: 1322-33 Citation Subset: AIM; IM |
Affiliation:
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Department of Physiological Sciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom. d.t.thwaites@ncl.ac.uk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Biological Transport Caco-2 Cells Carrier Proteins / physiology* Cyclic AMP / physiology Cyclic AMP-Dependent Protein Kinases / physiology Dipeptides / metabolism* Forskolin / pharmacology Humans Hydrogen-Ion Concentration Intestinal Absorption* Intestinal Mucosa / metabolism Phosphoproteins / genetics RNA, Messenger / analysis Sodium-Hydrogen Antiporter / physiology* Symporters* Vasoactive Intestinal Peptide / metabolism |
| Chemical | |
Reg. No./Substance:
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0/Carrier Proteins; 0/Dipeptides; 0/Phosphoproteins; 0/RNA, Messenger; 0/SLC15A1 protein, human; 0/Sodium-Hydrogen Antiporter; 0/Symporters; 0/growth factor-activatable Na-H exchanger NHE-1; 0/sodium-hydrogen exchanger 3; 0/sodium-hydrogen exchanger regulatory factor; 37221-79-7/Vasoactive Intestinal Peptide; 60-92-4/Cyclic AMP; 66428-89-5/Forskolin; EC 2.7.11.11/Cyclic AMP-Dependent Protein Kinases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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