Suppression by phenytoin of convulsant-induced afterdischarges at presynaptic nerve terminals

Gavriel David, Michael E. Selzer, Yoel Yaari

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The mechanisms underlying the induction of afterdischarges at presynaptic nerve terminal by convulsant aminopyridines and their suppression by the anticonvulsant drug phenytoin were studied at the frog neuromusclar preparation. Addition of aminopyridine to the perfusing solution induced the appearance of afterdischarges in motor nerve fibres following their primary response to a single nerve stimulus. The afterdischarges seemed to originate at or near the nerve terminals and to propagate both antidromically and orthodromically. The latter resulted in repetitive activation of the neuromuscular synapse. Focal recordings of nerve terminal potentials suggested that aminopyridines may induce afterdischarges by slowing spike repolarization and thereby producing a prolonged depolarization of nerve terminals. Phenytoin suppressed the aminopyridine-induced afterdischarges and the resultant repetitive excitation of the postsynaptic muscle fibres. This effect of phenytoin was associated with a depression of the action potential at the motor nerve terminals but not at their parent axons. These results single the presynaptic nerve terminals as preferential sites for convulsant and anti-convulsant actions.

Original languageEnglish
Pages (from-to)57-65
Number of pages9
JournalBrain Research
Volume339
Issue number1
DOIs
StatePublished - Jul 22 1985
Externally publishedYes

Fingerprint

Aminopyridines
Convulsants
Presynaptic Terminals
Phenytoin
Nerve Fibers
Anura
Anticonvulsants
Synapses
Action Potentials
Axons
Muscles

Keywords

  • afterdischarges
  • aminopyridine
  • anticonvulsant
  • convulsant
  • frog
  • neuromuscular junction
  • phenytoin

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)

Cite this

Suppression by phenytoin of convulsant-induced afterdischarges at presynaptic nerve terminals. / David, Gavriel; Selzer, Michael E.; Yaari, Yoel.

In: Brain Research, Vol. 339, No. 1, 22.07.1985, p. 57-65.

Research output: Contribution to journalArticle

David, Gavriel ; Selzer, Michael E. ; Yaari, Yoel. / Suppression by phenytoin of convulsant-induced afterdischarges at presynaptic nerve terminals. In: Brain Research. 1985 ; Vol. 339, No. 1. pp. 57-65.
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