Epilepsy Research
Volume 22, Issue 2 , Pages 137-144, October 1995

Evidence for decreased calcium dependent potassium conductance in hippocampal CA3 neurons of genetically epilepsy-prone rats

  • Suneeta Verma-Ahuja

      Affiliations

    • Department of Surgery, Division of Neurosurgery, Southern Illinois University School of Medicine, Springfield, IL 62794, USA
    • ,
  • M. Steven Evans

      Affiliations

    • Department of Neurology, Southern Illinois University School of Medicine, Springfield, IL 62794, USA
    • ,
  • Terrence Lyle Pencek

      Affiliations

    • Corresponding Author InformationCorresponding author. SIU School of Medicine, Department of Surgery, P.O. Box 19230, 800 N. Rutledge, Springfield, IL 62794-1312, USA.
    • Department of Surgery, Division of Neurosurgery, Southern Illinois University School of Medicine, Springfield, IL 62794, USA

Received 9 January 1995; received in revised form 26 June 1995; accepted 26 June 1995.

Abstract 

The genetically epilepsy-prone rat (GEPR) has become an important model to study genetic predisposition to epilepsy involving not only the brainstem but also forebrain structures. Previous work in CA1 hippocampal cells showed a reduction in spike frequency adaptation and only subtle changes in slow afterhyperpolarization (AHP). As important differences exist in calcium dependent potentials in the CA1 and CA3 hippocampal cells, we compared the membrane properties of hippocampal CA3 cells in GEPRs and Sprague-Dawley (SD) rats. There was no significant difference in the resting membrane potential, input resistance, charging time constant or rheobase between GEPRs and SD rat neurons. The action potential amplitude and the width at half maximal amplitude did not differ. A marked reduction in spike frequency adaptation accompanied by a very significant reduction in AHP was seen in the GEPR rats. Since calcium dependent potassium conductance produces both spike frequency adaptation and AHP, our results suggest that this conductance is reduced in the GEPR CA3 neurons.

Keywords:  Genetic epilepsy, GEPR, Hippocampus, Afterhyperpolarization, Adaptation, Calcium dependent potassium conductance

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PII: 0920-1211(95)00040-2

Epilepsy Research
Volume 22, Issue 2 , Pages 137-144, October 1995

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