Neurotransmitter release and its facilitation in crayfish - I. Saturation kinetics of release, and of entry and removal of calcium

H. Parnas*, J. Dudel, I. Parnas

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

Release and facilitated release of transmitter at neuromuscular junctions of the crayfish Astacus were measured as a function of [Ca]0 at single junctions using a patch clamp technique. Tests were made of a quantitative model that relates release of transmitter to [Ca]i. The model assumes three processes, entry of Ca during the action potential, release of transmitter as a function of [Ca]i, and removal of Ca after the action potential. Each process is decribed alternatively by linear kinetics or saturation kinetics, and predictions for different combinations of the equations are given. The main findings were in agreement with those predicted by the "saturation" model. The amplitude of synaptic current varies non-linearly with [Ca]0, log-log plot yielding a slope of about 1.6. The degree of facilitation at long intervals is an increasing function of [Ca]0. In addition, the duration of facilitation is prolonged as [Ca]0 is increased, to saturate at [Ca]0 of 9 mM.

Original languageEnglish
Pages (from-to)1-14
Number of pages14
JournalPflugers Archiv European Journal of Physiology
Volume393
Issue number1
DOIs
StatePublished - Mar 1982

Keywords

  • Calcium changes in terminals
  • Facilitation
  • Saturation kinetics
  • Synaptic transmitter release

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