Abstract
Inhibitory glycine receptors (GlyRs) are mainly expressed in the spinal cord and in the midbrain, where they control motor and sensory pathways. We describe here a fast potentiation of GlyR by intracellular Ca2+. This phenomenon was observed in rat spinal cord neurons and in transfected human cell lines. Potentiation develops in <100 ms, is proportional to Ca2+ influx, and is characterized by an increase in GlyR apparent affinity for glycine. Phosphorylation and G protein pathways appear not to be involved in the potentiation mechanism. Single-channel recordings in cell-attached and excised patches, as well as whole-cell data suggest the presence of a diffusible cytoplasmic factor that modulates the GlyR channel gating properties. Ca2+-induced potentiation may be important for rapid modulation of glycinergic synapses.
MeSH terms
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Animals
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Calcium / metabolism*
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Calcium / pharmacology
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Cells, Cultured
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Cytoplasm / metabolism
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Dose-Response Relationship, Drug
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Egtazic Acid / analogs & derivatives*
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Enzyme Inhibitors / pharmacology
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GTP-Binding Proteins / metabolism
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Glycine / metabolism
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Glycine / pharmacology
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Humans
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Intracellular Fluid / metabolism*
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Ion Channel Gating / drug effects
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Kidney
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Neurons / cytology
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Neurons / drug effects
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Neurons / metabolism*
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Patch-Clamp Techniques
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Phosphorylation / drug effects
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Rats
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Rats, Sprague-Dawley
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Reaction Time / drug effects
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Receptors, AMPA / metabolism
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Receptors, Glycine / drug effects
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Receptors, Glycine / genetics
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Receptors, Glycine / metabolism*
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Spinal Cord
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Time
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Transfection
Substances
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Enzyme Inhibitors
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Receptors, AMPA
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Receptors, Glycine
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Egtazic Acid
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GTP-Binding Proteins
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1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
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Calcium
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Glycine