title: Carisbamate blockade of T-type voltage-gated calcium channels.
abstract: 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.
  
  
  
  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+]ilevels through actions on the endoplasmic reticulum (ER), mitochondria, and/or T-type voltage-gated Ca2+channels.
  
  
  
  In CA3 pyramidal neurons, kainic acid induced significant elevations in [Ca2+]iand 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.
  
  
  
  Our data indicate that the neuroprotective and antiseizure activity of CRS likely results in part from decreased [Ca2+]iaccumulation through blockade of T-type Ca2+channels.
authors.affiliation: Departments of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital & Medical Center, Phoenix, Arizona, U.S.A.
authors.forename: Do Young
authors.initials: DY
authors.lastname: Kim
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.|Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Fang-Xiong
authors.initials: FX
authors.lastname: Zhang
authors.affiliation: Department of Biology, University of Hawaii at Hilo, Hilo, Hawaii, U.S.A.
authors.forename: Stan T
authors.initials: ST
authors.lastname: Nakanishi
authors.affiliation: Departments of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital & Medical Center, Phoenix, Arizona, U.S.A.
authors.forename: Timothy
authors.initials: T
authors.lastname: Mettler
authors.affiliation: Departments of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital & Medical Center, Phoenix, Arizona, U.S.A.
authors.forename: Ik-Hyun
authors.initials: IH
authors.lastname: Cho
authors.affiliation: Department of Pediatrics, University of Calgary, Calgary, Alberta, Canada.|Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Younghee
authors.initials: Y
authors.lastname: Ahn
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.|Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Florian
authors.initials: F
authors.lastname: Hiess
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Lina
authors.initials: L
authors.lastname: Chen
authors.affiliation: Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky, U.S.A.
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Sullivan
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.|Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: S R Wayne
authors.initials: SR
authors.lastname: Chen
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.|Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Zamponi
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.|Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.|Department of Pediatrics, University of Calgary, Calgary, Alberta, Canada.|Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.|Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Jong M
authors.initials: JM
authors.lastname: Rho
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000235:genetics / Q000378:metabolism*; D002219:Carbamates / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D057809:HEK293 Cells; D006624:Hippocampus / Q000166:cytology; D006801:Humans; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D009474:Neurons / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D010880:Piperidines / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D014162:Transfection
chemical_list: C481395:4-aminopiperidine; D000927:Anticonvulsants; D020747:Calcium Channels, T-Type; D002219:Carbamates; D018690:Excitatory Amino Acid Agonists; D010880:Piperidines; D026902:Potassium Channel Blockers; C518914:S-2-O-carbamoyl-1-o-chlorophenyl-ethanol; D018698:Glutamic Acid; D007608:Kainic Acid; D002118:Calcium
keywords: Calcium; Carisbamate; Endoplasmic reticulum; Kainic acid; Mechanism; Mitochondria; Neuroprotection; Ryanodine receptor; T-type calcium channel