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Persistent inward currents in rat ventral horn neurones
Author(s) -
Theiss Renée D.,
Kuo Jason J.,
Heckman C. J.
Publication year - 2007
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2006.124123
Subject(s) - bursting , neuroscience , spinal cord , sodium channel , chemistry , biophysics , tetrodotoxin , electrophysiology , sodium , biology , anatomy , organic chemistry
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.