Properties of Electrogenic Glutamate Uptake in Retinal Glia
In the dark photoreceptors have a membrane potential of about -40mV. At this potential they continuously release neurotransmitter molecules onto bipolar and horizontal cells. When a photoreceptor absorbs light the membrane hyperpolarises (to a maximum of about —70mV) and the release of neurotransmitter is suppressed. The transmitter released by photoreceptors is thought to be glutamate (Marc and Lam, 1981; Brandon and Lam, 1983; Miller and Schwartz, 1983; Ayoub et al., 1988). The light-induced suppression of glutamate release from photoreceptors results in a voltage change in postsynaptic bipolar and horizontal cells. The speed of onset of the postsynaptic response is determined (at least partly) by how quickly the extracellular concentration of glutamate falls when release from photoreceptors is suppressed.
KeywordsGlutamate Uptake Horizontal Cell Muller Cell Retinal Glial Cell Amino Acid Transmitter
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- Attwell, D., Barbour, B. and Brew, H., 1988, The effect of internal ions on electrogenic glutamate uptake in glial cells isolated from the tiger salamander retina, J. Physiol. Lond., 401:92P.Google Scholar
- Ayoub, G. S., Korenbrot, J. I. and Copenhagen D. R., 1988, Glutamate is released from individual photoreceptors, Investig. Ophthalmol. Suppl., 29:273.Google Scholar
- Hamberger, A., Berthold, C., Karlsson, B., Lehmann, A. and Nystrom, B., 1983, Extracellular GABA, Glutamate and Glutamine in vivo- perfusion dialysis of the rabbit hippocampus, in: “Glutamine, Glutamate and GABA in the Central Nervous System”, Hertz, L., Kvamme, E., McGeer, E. G. and Schousboe, A., ed., Alan R. Liss, NY.Google Scholar