Miniature postsynaptic currents depend on Ca2+ released from internal stores via PLC/IP3 pathway

Neuroreport. 2001 Jul 20;12(10):2203-7. doi: 10.1097/00001756-200107200-00032.


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

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Caffeine / pharmacology
  • Calcium / physiology*
  • Calcium Channels / metabolism
  • Calcium Signaling / physiology*
  • Cells, Cultured
  • Enzyme Inhibitors / pharmacology
  • Estrenes / pharmacology
  • Excitatory Postsynaptic Potentials / drug effects
  • Excitatory Postsynaptic Potentials / physiology*
  • Inositol 1,4,5-Trisphosphate / metabolism
  • Inositol 1,4,5-Trisphosphate / physiology*
  • Inositol 1,4,5-Trisphosphate Receptors
  • Phosphodiesterase Inhibitors / pharmacology
  • Pyrrolidinones / pharmacology
  • Rats
  • Rats, Long-Evans
  • Receptors, Cytoplasmic and Nuclear / metabolism
  • Retinal Ganglion Cells / drug effects
  • Retinal Ganglion Cells / metabolism*
  • Thapsigargin / pharmacology
  • Type C Phospholipases / metabolism*


  • Calcium Channels
  • Enzyme Inhibitors
  • Estrenes
  • Inositol 1,4,5-Trisphosphate Receptors
  • Phosphodiesterase Inhibitors
  • Pyrrolidinones
  • Receptors, Cytoplasmic and Nuclear
  • 1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione
  • Caffeine
  • Thapsigargin
  • Inositol 1,4,5-Trisphosphate
  • Type C Phospholipases
  • Calcium