Block of potassium channels and facilitation of acetylcholine release at the neuromuscular junction by the venom of the scorpion, Pandinus imperator

D L Marshall, A L Harvey

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Venom from the scorpion Pandinus imperator potently and selectively blocks voltage-gated K+ channels in bullfrog neurones (Pappone, P. A. and Cahalan, M. D. 1987, J. Neurosci. 7, 3300-3305). Its effects on neuromuscular transmission have now been assessed. Twitch tension studies on chick biventer cervicis preparations showed that the venom (1 microgram/ml and above) significantly augmented responses to nerve but not muscle stimulation; there was little change in postjunctional sensitivity to cholinoceptor agonists or K+-induced depolarization. Electrophysiological studies on mouse triangularis sterni preparations revealed that the venom had no effect on spontaneous transmitter release, but increased evoked transmitter release. Extracellular recordings of nerve terminal action potentials showed that the venom selectively reduced the component of the waveform associated with K+ currents. These results confirm that this venom can selectively block neuronal K+ currents, and they show that this can facilitate the release of acetylcholine at the neuromuscular junction.
Original languageEnglish
Pages (from-to)493-498
Number of pages6
JournalToxicon
Volume27
Issue number4
DOIs
Publication statusPublished - 1989

Keywords

  • 4-aminopyridine
  • acetylcholine
  • action potentials
  • aminopyridines
  • animals
  • chickens
  • electrophysiology
  • male
  • mice
  • inbred BALB C mice
  • motor endplate
  • muscle contraction
  • neuromuscular junction
  • potassium channels
  • scorpion venoms
  • chemical stimulation

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