An electrophysiological study on the effects of Pa-1G (a phospholipase A(2)) from the venom of king brown snake, Pseudechis australis, on neuromuscular function

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The effects of Pa-1G, a phospholipase A(2) (PLA(2)) from the venom of the Australian king brown snake (Pseudechis australis) were determined on the release of acetylcholine, muscle resting membrane potential and motor nerve terminal action potential at mouse neuromuscular junction. Intracellular recording from endplate regions of mouse triangularis sterni nerve-muscle preparations revealed that Pa-1G (800 nM) significantly reduced the amplitude of endplate potentials within 10 min exposure. The quantal content of endplate potentials was decreased to 58+/-6% of control after 30 min exposure to 800 nM Pa-1G. The toxin also caused a partial depolarisation of mouse muscle fibres within 60 min exposure. Extracellular recording of action potentials at motor nerve terminals showed that Pa-1G reduced the waveforms associated with both sodium and potassium conductances. To investigate whether this was a direct or indirect effect of the toxin on these ionic currents, whole cell patch clamp experiments were performed using human neuroblastoma (SK-N-SH) cells and B82 mouse fibroblasts stably transfected with rKv1.2. Patch clamp recording experiments confirmed that potassium currents sensitive to alpha-dendrotoxin recorded from B82 cells and sodium currents in SK-N-SH cells were not affected by the toxin. Since neither facilitation of acetylcholine release at mouse neuromuscular junction nor depression of potassium currents in B82 cells has been observed, the apparent blockade of potassium currents at mouse motor nerve endings induced by the toxin is unlikely to be due to a selective block of potassium channels.
LanguageEnglish
Pages69-75
Number of pages6
JournalToxicon
Volume40
Issue number1
DOIs
Publication statusPublished - 2002

Fingerprint

Colubridae
Phospholipases A
Venoms
Potassium
Muscle
Neuromuscular Junction
Clamping devices
Acetylcholine
Sodium
Action Potentials
Potassium Channels
Depolarization
Fibroblasts
Muscles
Nerve Endings
Experiments
Membranes
Neuroblastoma
Membrane Potentials
Fibers

Keywords

  • phospholipase a2 toxin
  • neuromuscular transmission
  • nerve terminal action potential
  • sodium current
  • potassium currents
  • patch clamp
  • venom

Cite this

@article{26a77df4b195434f85d7d87035860312,
title = "An electrophysiological study on the effects of Pa-1G (a phospholipase A(2)) from the venom of king brown snake, Pseudechis australis, on neuromuscular function",
abstract = "The effects of Pa-1G, a phospholipase A(2) (PLA(2)) from the venom of the Australian king brown snake (Pseudechis australis) were determined on the release of acetylcholine, muscle resting membrane potential and motor nerve terminal action potential at mouse neuromuscular junction. Intracellular recording from endplate regions of mouse triangularis sterni nerve-muscle preparations revealed that Pa-1G (800 nM) significantly reduced the amplitude of endplate potentials within 10 min exposure. The quantal content of endplate potentials was decreased to 58+/-6{\%} of control after 30 min exposure to 800 nM Pa-1G. The toxin also caused a partial depolarisation of mouse muscle fibres within 60 min exposure. Extracellular recording of action potentials at motor nerve terminals showed that Pa-1G reduced the waveforms associated with both sodium and potassium conductances. To investigate whether this was a direct or indirect effect of the toxin on these ionic currents, whole cell patch clamp experiments were performed using human neuroblastoma (SK-N-SH) cells and B82 mouse fibroblasts stably transfected with rKv1.2. Patch clamp recording experiments confirmed that potassium currents sensitive to alpha-dendrotoxin recorded from B82 cells and sodium currents in SK-N-SH cells were not affected by the toxin. Since neither facilitation of acetylcholine release at mouse neuromuscular junction nor depression of potassium currents in B82 cells has been observed, the apparent blockade of potassium currents at mouse motor nerve endings induced by the toxin is unlikely to be due to a selective block of potassium channels.",
keywords = "phospholipase a2 toxin, neuromuscular transmission, nerve terminal action potential, sodium current, potassium currents, patch clamp, venom",
author = "M. Fatehi and E.G. Rowan and A.L. Harvey",
year = "2002",
doi = "10.1016/S0041-0101(01)00190-8",
language = "English",
volume = "40",
pages = "69--75",
journal = "Toxicon",
issn = "0041-0101",
number = "1",

}

TY - JOUR

T1 - An electrophysiological study on the effects of Pa-1G (a phospholipase A(2)) from the venom of king brown snake, Pseudechis australis, on neuromuscular function

AU - Fatehi, M.

AU - Rowan, E.G.

AU - Harvey, A.L.

PY - 2002

Y1 - 2002

N2 - The effects of Pa-1G, a phospholipase A(2) (PLA(2)) from the venom of the Australian king brown snake (Pseudechis australis) were determined on the release of acetylcholine, muscle resting membrane potential and motor nerve terminal action potential at mouse neuromuscular junction. Intracellular recording from endplate regions of mouse triangularis sterni nerve-muscle preparations revealed that Pa-1G (800 nM) significantly reduced the amplitude of endplate potentials within 10 min exposure. The quantal content of endplate potentials was decreased to 58+/-6% of control after 30 min exposure to 800 nM Pa-1G. The toxin also caused a partial depolarisation of mouse muscle fibres within 60 min exposure. Extracellular recording of action potentials at motor nerve terminals showed that Pa-1G reduced the waveforms associated with both sodium and potassium conductances. To investigate whether this was a direct or indirect effect of the toxin on these ionic currents, whole cell patch clamp experiments were performed using human neuroblastoma (SK-N-SH) cells and B82 mouse fibroblasts stably transfected with rKv1.2. Patch clamp recording experiments confirmed that potassium currents sensitive to alpha-dendrotoxin recorded from B82 cells and sodium currents in SK-N-SH cells were not affected by the toxin. Since neither facilitation of acetylcholine release at mouse neuromuscular junction nor depression of potassium currents in B82 cells has been observed, the apparent blockade of potassium currents at mouse motor nerve endings induced by the toxin is unlikely to be due to a selective block of potassium channels.

AB - The effects of Pa-1G, a phospholipase A(2) (PLA(2)) from the venom of the Australian king brown snake (Pseudechis australis) were determined on the release of acetylcholine, muscle resting membrane potential and motor nerve terminal action potential at mouse neuromuscular junction. Intracellular recording from endplate regions of mouse triangularis sterni nerve-muscle preparations revealed that Pa-1G (800 nM) significantly reduced the amplitude of endplate potentials within 10 min exposure. The quantal content of endplate potentials was decreased to 58+/-6% of control after 30 min exposure to 800 nM Pa-1G. The toxin also caused a partial depolarisation of mouse muscle fibres within 60 min exposure. Extracellular recording of action potentials at motor nerve terminals showed that Pa-1G reduced the waveforms associated with both sodium and potassium conductances. To investigate whether this was a direct or indirect effect of the toxin on these ionic currents, whole cell patch clamp experiments were performed using human neuroblastoma (SK-N-SH) cells and B82 mouse fibroblasts stably transfected with rKv1.2. Patch clamp recording experiments confirmed that potassium currents sensitive to alpha-dendrotoxin recorded from B82 cells and sodium currents in SK-N-SH cells were not affected by the toxin. Since neither facilitation of acetylcholine release at mouse neuromuscular junction nor depression of potassium currents in B82 cells has been observed, the apparent blockade of potassium currents at mouse motor nerve endings induced by the toxin is unlikely to be due to a selective block of potassium channels.

KW - phospholipase a2 toxin

KW - neuromuscular transmission

KW - nerve terminal action potential

KW - sodium current

KW - potassium currents

KW - patch clamp

KW - venom

UR - http://dx.doi.org/10.1016/S0041-0101(01)00190-8

U2 - 10.1016/S0041-0101(01)00190-8

DO - 10.1016/S0041-0101(01)00190-8

M3 - Article

VL - 40

SP - 69

EP - 75

JO - Toxicon

T2 - Toxicon

JF - Toxicon

SN - 0041-0101

IS - 1

ER -