Characterization of Glutamate Transporter Function in the Tiger Salamander Retina

Characterization of Glutamate Transporter Function in the Tiger Salamander Retina Glutamate transporters in the tiger salamander retina were studied by autoradiographic and intracellular recording techniques. When the retina was incubated with 15 μM l -( 3 H)glutamate, photoreceptors and Muller cells were labeled, indicating that these cells had high-affinity glutamate uptake transporters. A much higher dose of glutamate than kainate was required in the bath to produce the same membrane depolarization in horizontal cells (HCs), and the time course of glutamate-induced depolarization was much slower than that of the kainate-induced depolarization. Since glutamate is a substrate of glutamate transporters whereas kainate is not, we attribute these differences to the buffering of extracellular glutamate by glutamate transporters in the retina. d -asparate ( d -asp) increased the efficacy of bath-applied glutamate. Dihydrokainate (DHKA) exerted little effect on glutamate efficacy when applied alone, but it increased glutamate efficacy in the presence of d -asp. These results are consistent with the notion that glutamate transporters in Muller cells are d -asp sensitive and those in photoreceptors are DHKA and d -asp sensitive. Application of DHKA (1–2 mM) did not affect the dark membrane potential or the light responses in rods and cones, but it depolarized the HC dark membrane potential and reduced the HC peak and tail light responses. Our results suggest that DHKA-sensitive glutamate transporters in photoreceptors regulate glutamate levels in rod and cone synaptic clefts. They modulate dark membrane potential and the relative rod/cone inputs in retinal HCs. © 1997 Elsevier Science Ltd. All rights reserved. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Vision Research Elsevier

Characterization of Glutamate Transporter Function in the Tiger Salamander Retina

Vision Research, Volume 37 (7) – Apr 1, 1997

Loading next page...
 
/lp/elsevier/characterization-of-glutamate-transporter-function-in-the-tiger-0G4YI50MvJ
Publisher
Elsevier
Copyright
Copyright © 1997 Elsevier Science Ltd
ISSN
0042-6989
eISSN
1878-5646
D.O.I.
10.1016/S0042-6989(96)00231-3
Publisher site
See Article on Publisher Site

Abstract

Glutamate transporters in the tiger salamander retina were studied by autoradiographic and intracellular recording techniques. When the retina was incubated with 15 μM l -( 3 H)glutamate, photoreceptors and Muller cells were labeled, indicating that these cells had high-affinity glutamate uptake transporters. A much higher dose of glutamate than kainate was required in the bath to produce the same membrane depolarization in horizontal cells (HCs), and the time course of glutamate-induced depolarization was much slower than that of the kainate-induced depolarization. Since glutamate is a substrate of glutamate transporters whereas kainate is not, we attribute these differences to the buffering of extracellular glutamate by glutamate transporters in the retina. d -asparate ( d -asp) increased the efficacy of bath-applied glutamate. Dihydrokainate (DHKA) exerted little effect on glutamate efficacy when applied alone, but it increased glutamate efficacy in the presence of d -asp. These results are consistent with the notion that glutamate transporters in Muller cells are d -asp sensitive and those in photoreceptors are DHKA and d -asp sensitive. Application of DHKA (1–2 mM) did not affect the dark membrane potential or the light responses in rods and cones, but it depolarized the HC dark membrane potential and reduced the HC peak and tail light responses. Our results suggest that DHKA-sensitive glutamate transporters in photoreceptors regulate glutamate levels in rod and cone synaptic clefts. They modulate dark membrane potential and the relative rod/cone inputs in retinal HCs. © 1997 Elsevier Science Ltd. All rights reserved.

Journal

Vision ResearchElsevier

Published: Apr 1, 1997

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create folders to
organize your research

Export folders, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off