Persistent inward currents in rat ventral horn neurones

Renée D. Theiss, Jason J. Kuo, C. J. Heckman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


Throughout the mammalian spinal cord, interneurones have been shown to exhibit distinct firing patterns in response to a step of injected current. In this study of ventral horn interneurones in a thick slice preparation of the lumbar cord of 11-19-day-old-rats, four distinct firing patterns were observed and classified as repetitive-firing, repetitive/burst, initial-burst or single-spiking. The hypothesis that a persistent sodium current was the predominant determinant of cell firing behaviour was investigated. A slow voltage ramp was used to assess persistent inward currents (PICs). Cells with repetitive-firing patterns had significantly larger PICs than cells displaying repetitive/ burst, initial-burst or single-spiking patterns. Repetitive-firing, repetitive/burst and initial-burst-firing cells were reduced to a single-spiking pattern with the application of riluzole, which also markedly reduced the persistent sodium current. Persistent sodium current was found to account for most of the PIC with only a small contribution from L-type calcium current. These results suggest that the persistent sodium current plays a major role in determining firing patterns in these cells.

Original languageEnglish (US)
Pages (from-to)507-522
Number of pages16
JournalJournal of Physiology
Issue number2
StatePublished - Apr 15 2007

ASJC Scopus subject areas

  • Physiology

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