Unique properties of R-type calcium currents in neocortical and neostriatal neurons

Robert C. Foehring, Paul G. Mermelstein, Wen Jie Song, Sasha Ulrich, D. James Surmeier

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Abstract

Whole cell recordings from acutely dissociated neocortical pyramidal neurons and striatal medium spiny neurons exhibited a calcium-channel current resistant to known blockers of L-, N-, and P/Q-type Ca2+ channels. These R-type currents were characterized as high-voltage-activated (HVA) by their rapid deactivation kinetics, half-activation and half-inactivation voltages, and sensitivity to depolarized holding potentials. In both cell types, the R-type current activated at potentials relatively negative to other HVA currents in the same cell type and inactivated rapidly compared with the other HVA currents. The main difference between cell types was that R-type currents in neocortical pyramidal neurons inactivated at more negative potentials than R-type currents in medium spiny neurons. Ni2+ sensitivity was not diagnostic for R-type currents in either cell type. Single-cell RT-PCR revealed that both cell types expressed the α1E mRNA, consistent with this subunit being associated with the R-type current.

Original languageEnglish (US)
Pages (from-to)2225-2236
Number of pages12
JournalJournal of neurophysiology
Volume84
Issue number5
StatePublished - Nov 29 2000

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Foehring, R. C., Mermelstein, P. G., Song, W. J., Ulrich, S., & Surmeier, D. J. (2000). Unique properties of R-type calcium currents in neocortical and neostriatal neurons. Journal of neurophysiology, 84(5), 2225-2236.