High-Resolution measurements of single-channel currents activated by glutamate in crayfish muscle

Ch Franke, J. Dudel

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Patch-clamp pipettes filled with 50-5000 μM glutamate were placed on crayfish muscle fibers treated with collagenase, formed GΩ seals and elicited single-channel currents with a main amplitude of about -8 pA at -70 mV membrane potential, representing a conductance of about 100 pS (19°C). Evaluation of the channel openings longer than 1 ms yielded three sublevels of this conductance. The channels opened in bursts, the durations of which were distributed in two exponential components with time constants of about 0.1 and 0.3 ms at low glutamate concentrations, which rose to about 0.4 and 1.8 ms, respectively, at high glutamate concentrations. The distributions of closed times could be described by three time constants which also varied with glutamate concentration. Comparison of the burst durations with the decay time constants of natural synaptic currents indicates effective glutamate concentrations in the millimolar range during transmission.

Original languageEnglish
Pages (from-to)241-246
Number of pages6
JournalNeuroscience Letters
Volume59
Issue number3
DOIs
StatePublished - 6 Sep 1985

Keywords

  • crayfish neuromuscular junction
  • glutaminergic synapse
  • kinetics of channel opening
  • single synaptic channel
  • sublevels of channel current

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