Presynaptic Calcium Stores Underlie Large-Amplitude Miniature IPSCs and Spontaneous Calcium Transients

Nat Neurosci. 2000 Dec;3(12):1256-65. doi: 10.1038/81781.

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

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Calcium / deficiency*
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology*
  • Cerebellum / drug effects
  • Cerebellum / metabolism
  • Cerebellum / ultrastructure
  • Extracellular Space / drug effects
  • Extracellular Space / metabolism
  • Interneurons / drug effects
  • Interneurons / metabolism
  • Interneurons / ultrastructure
  • Intracellular Fluid / drug effects
  • Intracellular Fluid / metabolism
  • Kinetics
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Neural Inhibition / drug effects
  • Neural Inhibition / physiology*
  • Presynaptic Terminals / drug effects
  • Presynaptic Terminals / metabolism*
  • Presynaptic Terminals / ultrastructure
  • Rats
  • Reaction Time / drug effects
  • Reaction Time / physiology
  • Ryanodine / pharmacology
  • Ryanodine Receptor Calcium Release Channel / drug effects
  • Ryanodine Receptor Calcium Release Channel / metabolism*
  • Synaptic Vesicles / drug effects
  • Synaptic Vesicles / metabolism*
  • Synaptic Vesicles / ultrastructure
  • Tetrodotoxin / pharmacology

Substances

  • Ryanodine Receptor Calcium Release Channel
  • Ryanodine
  • Tetrodotoxin
  • Calcium