Abstract

Objectives

Carisbamate (CRS) is a novel monocarbamate compound that possesses antiseizure and neuroprotective properties. However, the mechanisms underlying these actions remain unclear. Here, we tested both direct and indirect effects of CRS on several cellular systems that regulate intracellular calcium concentration [Ca2+]i.

Methods

We used a combination of cellular electrophysiologic techniques, as well as cell viability, Store Overload‐Induced Calcium Release (SOICR), and mitochondrial functional assays to determine whether CRS might affect [Ca2+]i levels through actions on the endoplasmic reticulum (ER), mitochondria, and/or T‐type voltage‐gated Ca2+ channels.

Results

In CA3 pyramidal neurons, kainic acid induced significant elevations in [Ca2+]i and long‐lasting neuronal hyperexcitability, both of which were reversed in a dose‐dependent manner by CRS. Similarly, CRS suppressed spontaneous rhythmic epileptiform activity in hippocampal slices exposed to zero‐Mg2+ or 4‐aminopyridine. Treatment with CRS also protected murine hippocampal HT‐22 cells against excitotoxic injury with glutamate, and this was accompanied by a reduction in [Ca2+]i. Neither kainic acid nor CRS alone altered the mitochondrial membrane potential (ΔΨ) in intact, acutely isolated mitochondria. In addition, CRS did not affect mitochondrial respiratory chain activity, Ca2+‐induced mitochondrial permeability transition, and Ca2+ release from the ER. However, CRS significantly decreased Ca2+ flux in human embryonic kidney tsA‐201 cells transfected with Cav3.1 (voltage‐dependent T‐type Ca2+) channels.

Significance

Our data indicate that the neuroprotective and antiseizure activity of CRS likely results in part from decreased [Ca2+]i accumulation through blockade of T‐type Ca2+ channels.

Document Type

Article

Publication Date

4-2017

Notes/Citation Information

Published in Epilepsia, v. 58, issue 4, p. 617-626.

Wiley Periodicals, Inc. © 2017 International League Against Epilepsy

The copyright holder has granted the permission for posting the article here.

This is the peer reviewed version of the following article: Kim, D. Y., Zhang, F. -X., Nakanishi, S. T., Mettler, T., Cho, I. -H., Ahn, Y., ... Rho, J. M. (2017). Carisbamate blockade of T‐type voltage‐gated calcium channels. Epilepsia, 58(4), 617-626, which has been published in final form at https://doi.org/10.1111/epi.13710. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Digital Object Identifier (DOI)

https://doi.org/10.1111/epi.13710

Funding Information

This work is supported by Johnson & Johnson Pharmaceutical Research (JMR), the Barrow Neurological Foundation (DYK), NIH grant NS070261 (JMR, DYK), the Alberta Children’s Hospital Research Institute (SN, JMR), the Canada Foundation for Innovation (SRWC), the Heart and Stroke Foundation/Libin Professorship in Cardiovascular Research (SRWC), the Natural Sciences and Engineering Research Council of Canada (SRWC), and the Canadian Institutes of Health Research (SRWC, GWZ, JMR). FXZ was supported by a fellowship from Alberta Innovates Health Solutions.

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