PMID- 14977334
OWN - NLM
STAT- MEDLINE
DCOM- 20040329
LR  - 20190917
IS  - 0952-5238 (Print)
IS  - 0952-5238 (Linking)
VI  - 20
IP  - 5
DP  - 2003 Sep-Oct
TI  - Activation of glutamate transporters in rods inhibits presynaptic calcium 
      currents.
PG  - 557-66
AB  - We found that L-glutamate (L-Glu) inhibits L-type Ca2+ currents (ICa) in rod 
      photoreceptors. This inhibition was studied in isolated rods or rods in retinal 
      slices from tiger salamander using perforated patch whole cell recordings and 
      Cl(-)-imaging techniques. Application of L-Glu inhibited ICa by approximately 20% 
      at 0.1 mM and approximately 35% at 1 mM. L-Glu also produced an inward current 
      that reversed around ECl. The metabotropic glutamate receptor (mGluR) agonists 
      t-ADA (Group I), DCG-IV (Group II), and L-AP4 (Group III) had no effect on ICa. 
      However, the glutamate transport inhibitor, TBOA (0.1 mM), prevented L-Glu from 
      inhibiting ICa. D-aspartate (D-Asp), a glutamate transporter substrate, also 
      inhibited ICa with significantly more inhibition at 1 mM than 0.1 mM. Using Cl 
      imaging, L-Glu (0.1-1 mM) and D-Asp (0.1-1 mM) were found to stimulate a Cl- 
      efflux from terminals of isolated rods whereas the ionotropic glutamate receptor 
      agonists NMDA, AMPA, and kainate and the mGluR agonist, 1S,3R-ACPD, did not. 
      Glutamate-evoked Cl- effluxes were blocked by the glutamate transport inhibitors 
      TBOA and DHKA. Cl- efflux inhibits Ca2+ channel activity in rod terminals 
      (Thoreson et al. (2000), Visual Neuroscience 17, 197). Consistent with the 
      possibility that glutamate-evoked Cl- efflux may play a role in the inhibition, 
      reducing intraterminal Cl- prevented L-Glu from inhibiting ICa. In summary, the 
      results indicate that activation of glutamate transporters inhibits ICa in rods 
      possibly as a consequence of Cl- efflux. The neurotransmitter L-Glu released from 
      rod terminals might thus provide a negative feedback signal to inhibit further 
      L-Glu release.
FAU - Rabl, Katalin
AU  - Rabl K
AD  - Department of Ophthalmology, University of Nebraska Medical Center, Omaha 
      68198-5540, USA.
FAU - Bryson, Eric J
AU  - Bryson EJ
FAU - Thoreson, Wallace B
AU  - Thoreson WB
LA  - eng
GR  - R01 EY010542/EY/NEI NIH HHS/United States
GR  - R01 EY010542-08/EY/NEI NIH HHS/United States
GR  - EY-10542/EY/NEI NIH HHS/United States
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - Vis Neurosci
JT  - Visual neuroscience
JID - 8809466
RN  - 0 (2-amino-4-phosphono-propinate)
RN  - 0 (Amino Acid Transport System X-AG)
RN  - 0 (Anticonvulsants)
RN  - 0 (Calcium Channels)
RN  - 0 (Cyclopropanes)
RN  - 0 (Propionates)
RN  - 0 (benzyloxyaspartate)
RN  - 127310-57-0 (azetidine-2,4-dicarboxylic acid)
RN  - 147782-19-2 (2-(2,3-dicarboxycyclopropyl)glycine)
RN  - 30KYC7MIAI (Aspartic Acid)
RN  - 3KX376GY7L (Glutamic Acid)
RN  - 4SR0Q8YD1X (D-Aspartic Acid)
RN  - 52497-36-6 (dihydrokainic acid)
RN  - 5GZ3E0L9ZU (Azetidinecarboxylic Acid)
RN  - SIV03811UC (Kainic Acid)
RN  - SY7Q814VUP (Calcium)
RN  - TE7660XO1C (Glycine)
SB  - IM
MH  - Amino Acid Transport System X-AG/antagonists & inhibitors/*metabolism
MH  - Animals
MH  - Anticonvulsants/pharmacology
MH  - Aspartic Acid/pharmacology
MH  - Azetidinecarboxylic Acid/*analogs & derivatives/pharmacology
MH  - Calcium/*metabolism
MH  - Calcium Channels/drug effects
MH  - Calcium Signaling/drug effects/*physiology
MH  - Cells, Cultured
MH  - Cyclopropanes/pharmacology
MH  - D-Aspartic Acid/pharmacology
MH  - Dose-Response Relationship, Drug
MH  - Drug Interactions
MH  - Glutamic Acid/pharmacology
MH  - Glycine/*analogs & derivatives/pharmacology
MH  - In Vitro Techniques
MH  - Kainic Acid/*analogs & derivatives/pharmacology
MH  - Membrane Potentials/drug effects
MH  - Neural Conduction/drug effects
MH  - Neural Inhibition/drug effects
MH  - Patch-Clamp Techniques
MH  - Presynaptic Terminals/*drug effects
MH  - Propionates/pharmacology
MH  - Retinal Rod Photoreceptor Cells/*drug effects/metabolism
MH  - Urodela
EDAT- 2004/02/24 05:00
MHDA- 2004/03/30 05:00
CRDT- 2004/02/24 05:00
PHST- 2004/02/24 05:00 [pubmed]
PHST- 2004/03/30 05:00 [medline]
PHST- 2004/02/24 05:00 [entrez]
AID - S0952523803205095 [pii]
AID - 10.1017/s0952523803205095 [doi]
PST - ppublish
SO  - Vis Neurosci. 2003 Sep-Oct;20(5):557-66. doi: 10.1017/s0952523803205095.