PMID- 9886993
OWN - NLM
STAT- MEDLINE
DCOM- 19990309
LR  - 20190215
IS  - 0002-9513 (Print)
IS  - 0002-9513 (Linking)
VI  - 276
IP  - 1
DP  - 1999 Jan
TI  - Effects of pH changes on systems ASC and B in rabbit ileum.
PG  - G173-84
LID - 10.1152/ajpgi.1999.276.1.G173 [doi]
AB  - Influx of D-aspartate (D-Asp), L-glutamate (L-Glu), and serine (Ser) across the 
      brush-border membrane of the intact mucosa from rabbit ileum has been examined. 
      L-Glu influx is chloride independent and completely sodium dependent. D-Asp and 
      L-Glu share a transport system with a maximum transport rate of 1 micromol. cm-2. 
      h-1 and an apparent affinity constant (K1/2) of approximately 0.3 mM. The 
      function of this transport system is pH insensitive between pH 5.65 and 8.2, and 
      bipolar amino acids do not affect the way in which the transport system handles 
      D-Asp and L-Glu. The characteristics of this transport system match those of 
      system X-AG. L-Glu and Ser share a transporter for which the inhibitor constant 
      (Ki) of L-Glu against Ser decreases from 54 to 10 mM when pH is reduced from 7.2 
      to 5.65, while the maximum rate of transport remains unaffected at approximately 
      10 micromol. cm-2. h-1. The Ki values (5 mM) of Ser against L-Glu influx and the 
      L-Glu-sensitive contribution to Ser influx (0.8 micromol. cm-2. h-1 at 1 mM Ser) 
      are the same at both pH values. The L-Glu-sensitive transport of Ser together 
      with the contribution of system bo,+ account for approximately 50% of Ser influx 
      at pH 7.2. The remaining 50% can be ascribed to system B. Transport of Ser by 
      system B is reduced by >95% at pH 5.65. At pH 7. 2 Ki of Ser against transport of 
      leucine (Leu) by system B is 18 mM and Ki of Leu against transport of Ser is 1.7 
      mM. The low-affinity transport of L-Glu and the L-Glu-sensitive transport of Ser 
      are performed by an equivalent of system ASC. Supplementary experiments using the 
      jejunum confirm the validity of these results for a major portion of the rabbit 
      small intestine.
FAU - Munck, B G
AU  - Munck BG
AD  - Department of Medical Physiology, The Panum Institute, University of Copenhagen, 
      Denmark.
FAU - Munck, L K
AU  - Munck LK
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Am J Physiol
JT  - The American journal of physiology
JID - 0370511
RN  - 0 (Amino Acid Transport Systems)
RN  - 0 (Carrier Proteins)
RN  - 0 (Chlorides)
RN  - 30KYC7MIAI (Aspartic Acid)
RN  - 3KX376GY7L (Glutamic Acid)
RN  - 452VLY9402 (Serine)
RN  - 7YNJ3PO35Z (Hydrogen)
RN  - 9NEZ333N27 (Sodium)
SB  - IM
MH  - Amino Acid Transport Systems
MH  - Animals
MH  - Aspartic Acid/*metabolism
MH  - Biological Transport/physiology
MH  - Carrier Proteins/metabolism
MH  - Chlorides/physiology
MH  - Female
MH  - Glutamic Acid/*metabolism
MH  - Hydrogen/*metabolism
MH  - Hydrogen-Ion Concentration
MH  - Ileum/*metabolism
MH  - Jejunum/metabolism
MH  - Kinetics
MH  - Microvilli/metabolism
MH  - Rabbits
MH  - Serine/*metabolism
MH  - Sodium/physiology
EDAT- 1999/01/14 00:00
MHDA- 1999/01/14 00:01
CRDT- 1999/01/14 00:00
PHST- 1999/01/14 00:00 [pubmed]
PHST- 1999/01/14 00:01 [medline]
PHST- 1999/01/14 00:00 [entrez]
AID - 10.1152/ajpgi.1999.276.1.G173 [doi]
PST - ppublish
SO  - Am J Physiol. 1999 Jan;276(1):G173-84. doi: 10.1152/ajpgi.1999.276.1.G173.