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

Marshall, D L and Harvey, A L (1989) Block of potassium channels and facilitation of acetylcholine release at the neuromuscular junction by the venom of the scorpion, Pandinus imperator. Toxicon, 27 (4). pp. 493-498. ISSN 0041-0101

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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.

Item type: Article
ID code: 31683
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, Pharmacy and materia medica, Toxicology
Subjects: Medicine > Pharmacy and materia medica
Department: Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences
Related URLs:
    Depositing user: Pure Administrator
    Date Deposited: 13 Jul 2011 09:57
    Last modified: 05 Sep 2014 09:33
    URI: http://strathprints.strath.ac.uk/id/eprint/31683

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