Modeling spontaneous and evoked glutamate release of NMDA receptors
© Su et al; licensee BioMed Central Ltd. 2009
Published: 13 July 2009
Spontaneous synaptic fusion is a feature in all synapses. These random release events have been extremely instrumental in the analysis of unitary properties of neurotransmission. Here, we detail some modeling studies for the kinetic scheme of NMDA receptors in a synapse that was published in . In a synapse, spontaneous and action-potential-driven neurotransmitter release is assumed to activate the same set of postsynaptic receptors. However, new experiments using MK-801, a well characterized use-dependent blocker of NMDA receptors shows NMDA-receptor-mediated spontaneous miniature EPSCs (NMDA-mEPSCs) and NMDA-receptor-mediated evoked EPSCs (NMDA-eEPSCs) responded with very different characters . Modeling glutamate diffusion and NMDA receptor activation revealed that postsynaptic densities larger than ≈0.2 μm2 can accommodate two populations of NMDA receptors with primarily nonoverlapping responsiveness. Collectively, these results support the premise that spontaneous and evoked neurotransmissions activate distinct sets of NMDA receptors and signal independently to the postsynaptic side.
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