Document Detail

Dipeptide transport and hydrolysis in isolated loops of rat small intestine: effects of stereospecificity.
MedLine Citation:
PMID:  7602518     Owner:  NLM     Status:  MEDLINE    
1. Isolated jejunal loops of rat small intestine were perfused by a single pass of bicarbonate Krebs-Ringer solution containing either D- or L-phenylalanine or one of eight dipeptides formed from D- or L-alanine plus D- or L-phenylalanine. 2. At 0.5 mM L-phenylalanyl-L-alanine increased serosal phenylalanine appearance to forty times the control rate giving a value similar to that found with 0.5 mM free L-phenylalanine. No serosal dipeptide could be detected. 3. Perfusions with the two mixed dipeptides with N-terminal D-amino acids (D-alanyl-L-phenylalanine and D-phenylalanyl-L-alanine) gave rise to the appearance of intact dipeptides in the serosal secretions although there were substantial differences in their rates of absorption and subsequent hydrolysis. 4. L-Alanyl-D-phenylalanine was absorbed from the lumen three to five times as fast as L-phenylalanyl-D-alanine. At 1 mM L-alanyl-D-phenylalanine transferred D-phenylalanine across the epithelial layer at more than seven times the rate found with the same concentration of the free D-amino acid. 5. Perfusions with D-alanyl-D-phenylalanine or D-phenylalanyl-D-alanine showed that these two dipeptides are poor substrates for both transport and hydrolysis by the rat small intestine. 6. Analysis of mucosal tissue extracts after perfusion with the two mixed dipeptides with N-terminal D-amino acids revealed that both dipeptides were accumulated within the mucosa and suggested that exit across the basolateral membrane was rate limiting for transepithelial dipeptide transport.
N Lister; A P Sykes; P D Bailey; C A Boyd; J R Bronk
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of physiology     Volume:  484 ( Pt 1)     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1995 Apr 
Date Detail:
Created Date:  1995-08-10     Completed Date:  1995-08-10     Revised Date:  2010-08-25    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  173-82     Citation Subset:  IM    
Department of Biology, University of York, UK.
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MeSH Terms
Alanine / metabolism,  pharmacology
Dipeptides / metabolism*,  pharmacology
Intestinal Absorption
Intestine, Small / metabolism*
Jejunum / metabolism
Phenylalanine / metabolism,  pharmacology
Rats, Wistar
Time Factors
Grant Support
//Wellcome Trust
Reg. No./Substance:
0/Dipeptides; 56-41-7/Alanine; 63-91-2/Phenylalanine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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