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Modulation of High‐Voltage–Activated Calcium Channels in Dentate Granule Cells by Topiramate
Author(s) -
Zhang Xiaolei,
Velumian Alexander A.,
Jones Owen T.,
Carlen Peter L.
Publication year - 2000
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.1528-1157.2000.tb02173.x
Subject(s) - dentate gyrus , chemistry , patch clamp , voltage dependent calcium channel , calcium , biophysics , granule (geology) , topiramate , electrophysiology , neuroscience , hippocampal formation , biology , biochemistry , receptor , paleontology , organic chemistry , epilepsy
Summary: Purpose : In this study, we assessed the effects of topiramate (TPM) on high‐voltage‐activated calcium channel (HVACC) currents in vitro. Methods : HVACC currents were recorded from rat dentate gyrus granule cells by using whole‐cell patch‐clamp techniques. The biophysical properties of HVACCs were used to separate voltage‐activated Ca 2+ currents into different subtypes. Three concentrations of TPM were tested: 1, 10, and 50 μ M . Results : TPM inhibited L‐type currents and was more effective at 10 μ M than at 50 μ M , suggesting that there may be an optimal concentration at which TPM decreases L‐type currents. Non‐L‐type currents were transiently increased by TPM at a high concentration (50 μ M ). Conclusions : Because the location of L‐type calcium channels on soma and proximal dendrites gives these channels a crucial role in controlling dendritic excitability and in providing calcium for intracellular effectors, the decrease in the L‐type HVA Ca 2+ currents may be an important anticonvulsant mechanism of TPM.