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(NAS Colloquium) The Neurobiology of Pain (1999) / Chapter Skim
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Ion Channels Gated by Heat
Pages 7658-7663

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From page 7658...
... The sensory terminals are extremely fine and are embedded in a cellular matrix whose disruption during dissection releases the very signaling molecules that the nociceptor nerve terminal is designed to detect. The difficulty of isolating intact nociceptive nerve terminals has meant that studies on isolated nociceptors have all been on neuronal cell bodies.
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From page 7659...
... Nor is the response due to damage to the nociceptive neuron itself as might occur if heat were causing a breakdown in the plasma membrane and a consequent depolarization because the depolarization and actionpotential firing ceases immediately when the stimulus is withdrawn and because similar responses can be elicited again and again on repeated application of the heat stimulus. The reproducibility of the response in isolated nociceptors resembles that in other sensory receptors.
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From page 7660...
... The main division, of course, is between slowly conducting, unmyelinated nociceptive nerve fibers, which commonly respond to a wide range of stimuli (polymodal fibers) and more rapidly conducting myelinated nerve fibers, which frequently respond to a smaller subset of noxious stimuli, but amongst which heat-sensitive units are also commonly encountered (12, 13~.
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From page 7661...
... , and Its Relation to Heat Sensation. Capsaicin, the active ingredient of chili peppers, has been known for some time to depolarize nociceptive nerve terminals by a direct action on an ion channel (28~.
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From page 7662...
... It does not seem that any accessory protein or signaling pathway is needed to gate the channel, because heat-sensitive ion channels can be seen in cell-free membrane patches from nociceptors (11) and because VR1 functions as a heat receptor when heterologously expressed in HEK 293 cells or inXenopus oocytes (18, 19~.
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From page 7663...
... Colloquium Paper: Cesare et al.
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Key Terms

  • ion channels
  • isolated nociceptors
  • protein kinase
  • nociceptive nerve
  • membrane current

  • sensory neurons
  • cyclic nucleotides
  • action potentials
  • heat stimulus
  • capsaicin receptor

  • nerve terminal
  • nerve terminals
  • channel opening
  • heat receptor
  • nociceptive neuron

  • heat sensation
  • heat sensitivity
  • receptor subtype
  • lower temperatures
  • vanilloid receptor

  • nerve fibers
  • current activated
  • direct action
  • time constants
  • native heat

  • heatsensitive ion
  • cation channel
  • inward current
  • induce channel
  • power spectrum


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