Penicilin-induced triphasic modulation of GABAA receptor-operated chloride current in frog sensory neuron

Norihiro Katayama, Naofumi Tokutomi, Junichi Nabekura, Norio Akaike

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Effects of penicillin-G(PPCN) on GABA-evoked Cl- current (IGABA) were investigated in freshly dissociated frog sensory neurons by the use of the concentration-clamp technique combined with the suction-pipette method. Under conditions where the internal and external solutions allowed only Cl- permeability, PCN elicited triphasic modulation on IGABA, consisting of two modes of blockade on IGABA and a following rebound (rebound-like transient IGABA). Simultaneously applied PCN and GABA depressed IGABA immediately (phasic blockade), with the depressed IGABA slightly recovering in amplitude to achieve a stable level of blockade (tonic blockade). When a solution containing a mixture or PCN and GABA was quickly replaced by one containing GABA alone, a rebound-like transient Cl- current (IGABA) was evoked. Each component of the PCN actions on IGABA was PCN- and GABA-concentration-dependent. The reversal potential for each component of the PCN actions on GABA was close to the chloride equilibrium potential (ECl calculated using the Nernst equation. The current-voltage (I-V) relations for both the phasic and tonic blockade revealed inward rectification, while I-V curves for the control IGABA and the IR were outwardly rectified. The degree of IGABA-desensitization and the amplitude of the IR correlated well. The data suggest that partial removal of the GABAA receptor-desensitization may result in generation of the IR.

Original languageEnglish
Pages (from-to)249-255
Number of pages7
JournalBrain research
Volume595
Issue number2
DOIs
Publication statusPublished - 1992 Nov 13

Keywords

  • Frog sensory neuron
  • Penicillin
  • γ-Aminobutyric acid

ASJC Scopus subject areas

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

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