The time course of glutamate in the synaptic cleft

John D. Clements, Robin A.J. Lester, Gang Tong, Craig E. Jahr, Gary L. Westbrook

Research output: Contribution to journalArticlepeer-review

839 Scopus citations


The peak concentration and rate of clearance of neurotransmitter from the synaptic cleft are important determinants of synaptic function, yet the neurotransmitter concentration time course is unknown at synapses in the brain. The time course of free glutamate in the cleft was estimated by kinetic analysis of the displacement of a rapidly dissociating competitive antagonist from N-methyl-D-aspartate (NMDA) receptors during synaptic transmission. Glutamate peaked at 1.1 millimolar and decayed with a time constant of 1.2 milliseconds at cultured hippocampal synapses. This time course implies that transmitter saturates postsynaptic NMDA receptors. However, glutamate dissociates much more rapidly from α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. Thus, the time course of free glutamate predicts that dissociation contributes to the decay of the AMPA receptor-mediated postsynaptic current.

Original languageEnglish (US)
Pages (from-to)1498-1501
Number of pages4
Issue number5087
StatePublished - 1992

ASJC Scopus subject areas

  • General


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