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Acta Biologica Hungarica

, Volume 53, Issue 1–2, pp 105–123 | Cite as

Cadmium Ions Modulate Gaba Induced Currents in Molluscan Neurons

  • G. Molnár
  • J. Győri
  • J. SalánkiEmail author
  • Katalin S.-Rózsa
Article

Abstract

The effect of Cd2+, as one of the most widespread toxic environmental pollutants, was studied on γ-aminobutyric acid (GABA) evoked responses of identified neurons in the central nervous system of the pond snail. Lymnaea stagnalis L. (Gastropoda). In the experiments, the modulation of the action of GABA both on neuronal activity (current clamp recording) and on the a GABA activated membrane Cl-current (voltage clamp studies) has been shown. It was found that:
  1. 1.

    GABA could evoked three different various types of response in GABA sensitive neurons: i) hyperpolarization with strong inhibition of ongoing spike activity, ii) short depolarization with an increase of spike the activity, iii) biphasic respone with a short excitation followed by a more prolonged long inhibition.

     
  2. 2.

    In low-Cl solution the inhibitory action of GABA was reduced or eliminated, but the excitatory one was not or only moderately affected.

     
  3. 3.

    CdCl2 inhibited the GABA evoked hyperpolarization, but left intact or only slightly reduced the excitation evoked by GABA.

     
  4. 4.

    The inward Cl--current evoked by GABA at a −75 mV holding potential was slightly augmented in the presence of 1 μmol/l Cd2+, but was reduced or blocked at higher cadmium concentrations. The effect of Cd2+ was concentration and time dependent.

     
  5. 5.

    Parallel with reducing the GABA evoked current, cadmium increased both the time to peak and the half inactivation time of the current.

     
  6. 6.

    CdCl2 alone, in 50 μmol/l concentration, induced a 1–2 nA inward current.

     

The blocking effect of cadmium on GABA activated inhibitory processes can be an important component of the neurotoxic effects of this heavy metal ion.

Keywords

GABA Cd2+, Cl-current Lymnaea stagnalis L. 

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© Akadémiai Kiadó, Budapest 2002

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors and Affiliations

  • G. Molnár
    • 1
  • J. Győri
    • 1
  • J. Salánki
    • 1
    Email author
  • Katalin S.-Rózsa
    • 1
  1. 1.Balaton Limnological Research Institute of the Hungarian Academy of SciencesTihanyHungary

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