Potassium-induced enhancement of persistent inward current in hippocampal neurons in isolation and in tissue slices.

Published

Journal Article

Previous work suggested a role for the voltage-dependent persistent sodium current, I(Na,P), in the generation of seizures and spreading depression (SD). Ordinarily, I(Na,P) is small in hippocampal neurons. We investigated the effect of raising external K(+) concentration, [K(+)](o), on whole-cell persistent inward current in freshly isolated hippocampal CA1 pyramidal neurons. I(Na,P) was identified by TTX-sensitivity and dependence on external Na(+) concentration. When none of the ion channels were blocked, I(Na,P) was not usually detectable, probably because competing K(+) current masked it, but after raising [K(+)](o) I(Na,P) appeared, while K(+) currents diminished. With K(+) channels blocked, I(Na,P) could usually be evoked in control solution and raising [K(+)](o) caused its reversible increase in most cells. The increase did not depend on external calcium [Ca(2+)](o). In CA1 pyramidal neurons in hippocampal slices a TTX-sensitive persistent inward current was always recorded and when [K(+)](o) was raised, it was reversibly enhanced. Strong depolarization evoked irregular current fluctuations, which were also augmented in high [K(+)](o). The findings support a role of potassium-mediated positive feedback in the generation of seizures and spreading depression.

Full Text

Duke Authors

Cited Authors

  • Somjen, GG; Müller, M

Published Date

  • December 1, 2000

Published In

Volume / Issue

  • 885 / 1

Start / End Page

  • 102 - 110

PubMed ID

  • 11121535

Pubmed Central ID

  • 11121535

International Standard Serial Number (ISSN)

  • 0006-8993

Digital Object Identifier (DOI)

  • 10.1016/s0006-8993(00)02948-6

Language

  • eng

Conference Location

  • Netherlands