Abstract
Miniature postsynaptic currents (mPSCs) were examined on autaptic innervation of single rat retinal ganglion cells in low density cultures. Removal of Ca2+ from bath solution or blocking of Ca2+ channels by Cd2+ had no detectable effect on mPSC frequency or amplitude. Thapsigargin, an agent for mobilization of Ca2+ from internal stores, increased mPSC frequency 3-5-fold in control, Ca2+-free or Cd2+-containing solutions. The inositol 1,4,5-triphosphate (IP3) receptor antago- nist, heparin; the phospholipase C (PLC) inhibitor, U73122; and caffeine abolished mPSC or decreased mPSCs frequency. Calcium imaging showed that cytosolic Ca2+ was increased by thapsigargin and decreased by caffeine. These data demonstrate that internal store-released Ca2+ regulated by the PLC/IP3/IP3-receptor pathway has critical contribution to generation and control of miniature release in retinal ganglion cells.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Caffeine / pharmacology
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Calcium / physiology*
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Calcium Channels / metabolism
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Calcium Signaling / physiology*
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Cells, Cultured
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Enzyme Inhibitors / pharmacology
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Estrenes / pharmacology
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Excitatory Postsynaptic Potentials / drug effects
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Excitatory Postsynaptic Potentials / physiology*
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Inositol 1,4,5-Trisphosphate / metabolism
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Inositol 1,4,5-Trisphosphate / physiology*
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Inositol 1,4,5-Trisphosphate Receptors
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Phosphodiesterase Inhibitors / pharmacology
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Pyrrolidinones / pharmacology
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Rats
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Rats, Long-Evans
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Receptors, Cytoplasmic and Nuclear / metabolism
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Retinal Ganglion Cells / drug effects
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Retinal Ganglion Cells / metabolism*
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Thapsigargin / pharmacology
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Type C Phospholipases / metabolism*
Substances
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Calcium Channels
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Enzyme Inhibitors
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Estrenes
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Inositol 1,4,5-Trisphosphate Receptors
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Phosphodiesterase Inhibitors
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Pyrrolidinones
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Receptors, Cytoplasmic and Nuclear
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1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione
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Caffeine
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Thapsigargin
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Inositol 1,4,5-Trisphosphate
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Type C Phospholipases
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Calcium