Abstract
The cellular mechanisms responsible for large miniature currents in some brain synapses remain undefined. In Purkinje cells, we found that large-amplitude miniature inhibitory postsynaptic currents (mIPSCs) were inhibited by ryanodine or by long-term removal of extracellular Ca2+. Two-photon Ca2+ imaging revealed random, ryanodine-sensitive intracellular Ca2+ transients, spatially constrained at putative presynaptic terminals. At high concentration, ryanodine decreased action-potential-evoked rises in intracellular Ca2+. Immuno-localization showed ryanodine receptors in these terminals. Our data suggest that large mIPSCs are multivesicular events regulated by Ca2+ release from ryanodine-sensitive presynaptic Ca2+ stores.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Animals, Newborn
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Calcium / deficiency*
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Calcium Signaling / drug effects
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Calcium Signaling / physiology*
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Cerebellum / drug effects
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Cerebellum / metabolism
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Cerebellum / ultrastructure
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Extracellular Space / drug effects
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Extracellular Space / metabolism
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Interneurons / drug effects
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Interneurons / metabolism
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Interneurons / ultrastructure
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Intracellular Fluid / drug effects
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Intracellular Fluid / metabolism
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Kinetics
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Membrane Potentials / drug effects
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Membrane Potentials / physiology
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Neural Inhibition / drug effects
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Neural Inhibition / physiology*
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Presynaptic Terminals / drug effects
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Presynaptic Terminals / metabolism*
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Presynaptic Terminals / ultrastructure
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Rats
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Reaction Time / drug effects
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Reaction Time / physiology
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Ryanodine / pharmacology
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Ryanodine Receptor Calcium Release Channel / drug effects
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Ryanodine Receptor Calcium Release Channel / metabolism*
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Synaptic Vesicles / drug effects
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Synaptic Vesicles / metabolism*
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Synaptic Vesicles / ultrastructure
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Tetrodotoxin / pharmacology
Substances
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Ryanodine Receptor Calcium Release Channel
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Ryanodine
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Tetrodotoxin
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Calcium