Currents Activated by GABA and their Modulation by Zn2+ in Cerebellar Granule Cells in Culture

G. Kilic, O. Moran, E. Cherubini

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

Whole‐cell and single‐channel currents evoked by γ‐aminobutyric acid (GABA) were recorded from rat cerebellar granule cells in culture. The electro‐physiological properties of these currents were studied in control condition and in the presence of external Zn2+ (10 – 30μM). GABA (10 μM) induced bicuculline‐sensitive whole‐cell currents which desensitized. The desensitization was more rapid for higher concentrations of GABA (30 – 300 μM). The current – voltage relation of GABA currents was linear from – 70 to +50 mV. Two different types of cells were found with respect to the stoichiometry for agonist binding, one with Hill coefficient 1.5 and another one with coefficient 1. The half‐maximum concentration displayed more variability, with values varying from 10 to 50 μM. The time constant of recovery from desensitization (Tr) was estimated to be 36 s. Zn2+ (30 μM) blocked GABA‐activated whole‐cell currents in a non‐competitive and voltage‐independent way without a significant change in the current kinetics. In excised outside‐out patches, GABA (0.5 μM) activated single‐channel events of 19 and 31 pS. Kinetic analysis yielded two mean shut times (Tc1= 2.70 ms, Tc2= 205 ms) and one mean open time (To= 3.64 ms). Zn2+ (10 μM) did not affect single‐channel conductances and mean open and shut times, but significantly reduced the probability of opening from 0.17 to 0.06. It is probable that Zn2+ binds to a site located on the extracellular part of the GABAA receptor channel complex.

Original languageEnglish (US)
Pages (from-to)65-72
Number of pages8
JournalEuropean Journal of Neuroscience
Volume5
Issue number1
DOIs
StatePublished - Jan 1993

Keywords

  • GABA receptor
  • cerebellum
  • extracellular Zn
  • patch clamp
  • rat

ASJC Scopus subject areas

  • Neuroscience(all)

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