Abstract
We studied the effects of a wasp toxin beta-pompilidotoxin (beta-PMTX) on rat hippocampal CA1 interneurons by the current-clamp technique. The firing patterns of pyramidal neurons and pyramidale interneurons were not affected by beta-PMTX, but in oriens and radiatum interneurons, beta-PMTX converted the action potentials to prolonged depolarizing potentials by slowing the inactivation of Na(+) channels. In lacunosum moleculare interneurons, beta-PMTX induced initial bursting spikes followed by block of succeeding spikes. Comparison of beta-PMTX with a sea anemone toxin, ATX II, revealed that ATX II altered the firing properties of pyramidal neurons and pyramidale interneurons that were unchanged by beta-PMTX. Our results suggest that beta-PMTX modulates Na(+) currents in CA1 interneurons differently in various CA1 neurons and the toxin is useful to classify Na(+) channel subtypes.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Action Potentials / drug effects
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Action Potentials / physiology*
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Animals
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Cnidarian Venoms / pharmacology
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Excitatory Postsynaptic Potentials / drug effects
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Excitatory Postsynaptic Potentials / physiology
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Hippocampus / cytology
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Hippocampus / drug effects
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Hippocampus / metabolism*
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Insect Proteins
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Interneurons / cytology
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Interneurons / drug effects
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Interneurons / metabolism*
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Male
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Neural Inhibition / drug effects
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Neural Inhibition / physiology*
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Neural Pathways / cytology
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Neural Pathways / drug effects
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Neural Pathways / metabolism
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Neurotoxins / pharmacology*
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Organ Culture Techniques
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Pyramidal Cells / cytology
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Pyramidal Cells / drug effects
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Pyramidal Cells / metabolism*
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Rats
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Rats, Wistar
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Sodium Channels / drug effects
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Sodium Channels / metabolism*
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Synaptic Transmission / drug effects
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Synaptic Transmission / physiology
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Wasp Venoms
Substances
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Cnidarian Venoms
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Insect Proteins
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Neurotoxins
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Sodium Channels
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Wasp Venoms
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pompilidotoxin beta
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toxin II (Anemonia sulcata)