Single channel properties at the synaptic site

Part of the EXS book series (EXS, volume 63)


The properties of single channels activated during spontaneous postsynaptic currents in small cultured rat hippocampal neurons were investigated in low-noise whole cell recordings. The technique of nonstationary fluctuation analysis, which has previously been applied to sodium currents, was modified so that fluctuations were measured around the least-squares scaled fit of the ensemble average to individual synaptic currents. This had the effect of separating channel gating fluctuations from the quantal fluctuations of scale from event to event. Single channel amplitude was estimated from the variance — current distribution, and the kinetics of channel gating fluctuations were studied. Channels involved in the non-N-methyl-D-aspartate (non-NMDA) phase of the excitatory glutamatergic postsynaptic current showed a single channel amplitude of 1.5 pS, while those in the NMD A phase had a conductance of 42 pS. The single channel conductance estimated for the inhibitory chloride synaptic current was 14 pS. In addition, NMDA phase channel openings could be resolved directly in the whole cell current against the low noise level afforded by the small cells. Single channel lifetime and amplitude distributions of the channels activated during the postsynaptic current were measured, and confirmed the accuracy of the fluctuation method.


Single Channel Corner Frequency Synaptic Current Excitatory Postsynaptic Current Single Channel Current 
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Copyright information

© Birkhäuser Verlag Basel/Switzerland 1993

Authors and Affiliations

  1. 1.Laboratory of Material ScienceNTT Basic Research LaboratoriesMusashino-shi, Tokyo 180Japan
  2. 2.Department of PhysiologyJichi Medical SchoolMinamikawachi, Tochigi-kenJapan

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