PMID- 11287328
OWN - NLM
STAT- MEDLINE
DCOM- 20010517
LR  - 20200930
IS  - 0363-6143 (Print)
IS  - 0363-6143 (Linking)
VI  - 280
IP  - 5
DP  - 2001 May
TI  - Regulation of mitochondrial glutamine/glutamate metabolism by glutamate 
      transport: studies with (15)N.
PG  - C1151-9
AB  - We focused on the role of plasma membrane glutamate uptake in modulating the 
      intracellular glutaminase (GA) and glutamate dehydrogenase (GDH) flux and in 
      determining the fate of the intracellular glutamate in the proximal tubule-like 
      LLC-PK(1)-F(+) cell line. We used high-affinity glutamate transport inhibitors 
      D-aspartate (D-Asp) and DL-threo-beta-hydroxyaspartate (THA) to block 
      extracellular uptake and then used [(15)N]glutamate or [2-(15)N]glutamine to 
      follow the metabolic fate and distribution of glutamine and glutamate. In 
      monolayers incubated with [2-(15)N]glutamine (99 atom %excess), glutamine and 
      glutamate equilibrated throughout the intra- and extracellular compartments. In 
      the presence of 5 mM D-Asp and 0.5 mM THA, glutamine distribution remained 
      unchanged, but the intracellular glutamate enrichment decreased by 33% (P < 0.05) 
      as the extracellular enrichment increased by 39% (P < 0.005). With glutamate 
      uptake blocked, intracellular glutamate concentration decreased by 37% (P < 
      0.0001), in contrast to intracellular glutamine concentration, which remained 
      unchanged. Both glutamine disappearance from the media and the estimated 
      intracellular GA flux increased with the fall in the intracellular glutamate 
      concentration. The labeled glutamate and NH formed from [2-(15)N]glutamine and 
      recovered in the media increased 12- and 3-fold, respectively, consistent with 
      accelerated GA and GDH flux. However, labeled alanine formation was reduced by 
      37%, indicating inhibition of transamination. Although both D-Asp and THA alone 
      accelerated the GA and GDH flux, only THA inhibited transamination. These results 
      are consistent with glutamate transport both regulating and being regulated by 
      glutamine and glutamate metabolism in epithelial cells.
FAU - Welbourne, T
AU  - Welbourne T
AD  - Department of Molecular and Cellular Physiology, Louisiana State University 
      Medical Center, Shreveport, Louisiana 71130, USA. twelbo@lsumc.edu
FAU - Nissim, I
AU  - Nissim I
LA  - eng
GR  - DK-53761/DK/NIDDK NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Am J Physiol Cell Physiol
JT  - American journal of physiology. Cell physiology
JID - 100901225
RN  - 0 (Nitrogen Isotopes)
RN  - 0RH81L854J (Glutamine)
RN  - 1860-87-3 (3-hydroxyaspartic acid)
RN  - 30KYC7MIAI (Aspartic Acid)
RN  - 3KX376GY7L (Glutamic Acid)
RN  - 7664-41-7 (Ammonia)
RN  - EC 1.4.1.2 (Glutamate Dehydrogenase)
RN  - EC 3.5.1.2 (Glutaminase)
SB  - IM
MH  - Ammonia/metabolism
MH  - Animals
MH  - Aspartic Acid/analogs & derivatives/pharmacology
MH  - Cell Line
MH  - Cytosol/metabolism
MH  - Extracellular Space/physiology
MH  - Glutamate Dehydrogenase/metabolism
MH  - Glutamic Acid/*metabolism
MH  - Glutaminase/metabolism
MH  - Glutamine/*metabolism
MH  - Intracellular Fluid/physiology
MH  - Kidney Tubules, Proximal/*physiology
MH  - Kinetics
MH  - Mitochondria/drug effects/*metabolism
MH  - Models, Chemical
MH  - Nitrogen Isotopes
MH  - Stereoisomerism
EDAT- 2001/04/05 10:00
MHDA- 2001/05/22 10:01
CRDT- 2001/04/05 10:00
PHST- 2001/04/05 10:00 [pubmed]
PHST- 2001/05/22 10:01 [medline]
PHST- 2001/04/05 10:00 [entrez]
AID - 10.1152/ajpcell.2001.280.5.C1151 [doi]
PST - ppublish
SO  - Am J Physiol Cell Physiol. 2001 May;280(5):C1151-9. doi: 
      10.1152/ajpcell.2001.280.5.C1151.