Abstract
The pharmacological characteristics of [3H]dofetilide binding in SHSY5Y, HEK293 and CHO-K1 cells were examined, and in parallel whole cell recordings used to characterise HERG-like K+ currents. Dofetilide affinity was similar in the human cell lines, SHSY5Y (Kd=99.6 nM) and HEK293 (Kd=102.9 nM), but 10 times lower in CHO-K1 cells (Kd=1200 nM). In contrast, clofilium and E4031 had a similar affinity in all three cell lines, whereas WAY 123,398 had no effect. Electrophysiological studies showed that SHSY5Y cells contained a HERG-like K+ current blocked by application of dofetilide to either side of the membrane. Block was faster when dofetilide was applied intracellularly. In contrast, HEK293 and CHO-K1 cells contained no such current, despite the presence of a partial cDNA for HERG in the former. That [3H]dofetilide is specific for I(Kr)/HERG may be questionable, as HEK293 and CHO-K1 cells contain no such functional K+ current.
MeSH terms
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Animals
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Anti-Arrhythmia Agents / metabolism*
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Anti-Arrhythmia Agents / pharmacology
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Benzimidazoles / pharmacology
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Binding Sites
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Cation Transport Proteins*
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Cell Line
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DNA-Binding Proteins*
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Dose-Response Relationship, Drug
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ERG1 Potassium Channel
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Ether-A-Go-Go Potassium Channels
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Humans
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Membrane Potentials / drug effects
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Patch-Clamp Techniques
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Phenethylamines / metabolism*
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Phenethylamines / pharmacology
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Potassium Channel Blockers
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Potassium Channels / metabolism*
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Potassium Channels, Voltage-Gated*
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Protein Binding
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Quaternary Ammonium Compounds / pharmacology
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RNA / metabolism
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Radioligand Assay
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Sulfanilamides / pharmacology
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Sulfonamides / metabolism*
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Sulfonamides / pharmacology
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Trans-Activators*
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Transcriptional Regulator ERG
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Tumor Cells, Cultured
Substances
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Anti-Arrhythmia Agents
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Benzimidazoles
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Cation Transport Proteins
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DNA-Binding Proteins
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ERG protein, human
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ERG1 Potassium Channel
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Ether-A-Go-Go Potassium Channels
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KCNH2 protein, human
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KCNH6 protein, human
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Phenethylamines
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Potassium Channel Blockers
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Potassium Channels
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Potassium Channels, Voltage-Gated
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Quaternary Ammonium Compounds
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Sulfanilamides
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Sulfonamides
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Trans-Activators
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Transcriptional Regulator ERG
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WAY 123398
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RNA
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clofilium
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dofetilide