No change in NMDA receptor-mediated response rise-time during development: evidence against transmitter spillover.

TitleNo change in NMDA receptor-mediated response rise-time during development: evidence against transmitter spillover.
Publication TypeJournal Article
Year of Publication1998
AuthorsHaas K, Cline H, Malinow R
JournalNeuropharmacology
Volume37
Issue10-11
Pagination1393-8
Date Published1998 Oct-Nov
ISSN0028-3908
KeywordsAnimals, Larva, N-Methylaspartate, Patch-Clamp Techniques, Receptors, N-Methyl-D-Aspartate, Superior Colliculi, Synaptic Transmission, Xenopus
Abstract

Glutamatergic transmission was examined in tadpole optic tectum to test the possibility that transmitter concentration reaching N-methyl-D-aspartate (NMDA) receptors increases over development. Pharmacologically isolated NMDA receptor-mediated transmission was monitored with whole-cell recordings. Synaptic responses were recorded from cells at different locations in the optic tectum, corresponding to different stages of development. Rise-times and decay-times of NMDA currents were analyzed. We found no significant correlation between rise-time and developmental stage. As NMDA rise-times can correlate with concentration for glutamate concentrations below 200 microM, these results argue that, if there is developmental variation in transmitter concentration, this occurs for values greater than 200 microM. Furthermore, we found a correlation between rise-times and decay-times, consistent with a model in which transmitter concentration is high and rise-time is controlled by channel closings. These results argue against synaptic models in which low concentrations of transmitter (as by spillover from nearby release sites) selectively activates NMDA receptors.

URLhttps://www.ncbi.nlm.nih.gov/pubmed/9849674
Alternate JournalNeuropharmacology
PubMed ID9849674