Presynaptic calcium stores underlie large-amplitude miniature IPSCs and spontaneous calcium transients.
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.
Llano
I
I
Arbeitsgruppe Zelluläre Neurobiologie, Max-Planck-Institut für biophysikalische Chemie, 37077 Göttingen, Germany. illano@gwdg.de
González
J
J
Caputo
C
C
Lai
F A
FA
Blayney
L M
LM
Tan
Y P
YP
Marty
A
A
D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000172:deficiency*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D007395:Interneurons / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012433:Ryanodine / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects / Q000378:metabolism*; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D013779:Tetrodotoxin / Q000494:pharmacology
D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D013779:Tetrodotoxin; D002118:Calcium