Tonic activation of NMDA receptors by ambient glutamate enhances excitability of neurons.
Voltage clamp recordings and noise analysis from pyramidal cells in hippocampal slices indicate that N-methyl-D-aspartate (NMDA) receptors are tonically active. On the basis of the known concentration of glutamate in the extracellular fluid, this tonic action is likely caused by the ambient glutamate level. NMDA receptors are voltage-sensitive, thus background activation of these receptors imparts a regenerative electrical property to pyramidal cells, which facilitates the coupling between dendritic excitatory synaptic input and somatic action potential discharge in these neurons.
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Department of Pharmacology, University of California, San Francisco 94143.
Hestrin
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Nicoll
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D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000200:Action Potentials; D000465:Algorithms; D000818:Animals; D001224:Aspartic Acid / Q000037:antagonists & inhibitors / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D006624:Hippocampus / Q000502:physiology*; D016018:Least-Squares Analysis; D008274:Magnesium / Q000494:pharmacology; D008839:Microelectrodes; D016202:N-Methylaspartate; D009474:Neurons / Q000502:physiology*; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000502:physiology*; D013569:Synapses / Q000502:physiology
D005971:Glutamates; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D001224:Aspartic Acid; D018698:Glutamic Acid; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D008274:Magnesium