Pflügers Archiv

, Volume 397, Issue 1, pp 13–19 | Cite as

Glutamate activated postsynaptic channels in crayfish muscle investigated by noise analysis

  • H. Stettmeier
  • W. Finger
  • J. Dudel
Excitable Tissues and Central Nervous Physiology

Abstract

Excitatory synaptic channels in crayfish muscle were investigated under various experimental conditions. Small muscle fibres of lengthl≤0.6 mm were voltage clamped, spatial control of the voltage being sufficient up to at least 500 Hz. Excitatory synaptic current was induced by superfusion of glutamate. The power density spectra of this current could be fitted by single component Lorentz curves. The analysis revealed a mean open time τnoise= 0.93 ms and a conductance γ=32.2 pS of the glutamate operated ion channels (membrane potentialE=−60mV, temperatureT=8°C). Both the conductance γ and the channel closing rate α=τ noise −1 increased significantly with temperature (Q10∼2). The temperature dependence of γ and α could be described by Arrhenius equations with the temperature independent activation energiesEγ=42.3 kJ/mol andEα=50.2 kJ/mol. α also depended on the membrane potential, increasing about e-fold when the membrane was hyperpolarized by 120 mV. The potential dependence varied considerably from fibre to fibre. The mean channel open time τnoise agreed with the time constant of decay τ(sEPSC) of spontaneous excitatory postsynaptic currents (sEPSCs).

Key words

Glutamate induced synaptic currents Excitatory synaptic channels Excitatory synaptic transmission Noise analysis Space clamp 

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Copyright information

© Springer-Verlag 1983

Authors and Affiliations

  • H. Stettmeier
    • 1
  • W. Finger
    • 1
  • J. Dudel
    • 1
  1. 1.Physiologisches Institut der Technischen Universität MünchenMünchen 40Germany

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