Advertisement

Electrophysiology of Corneal Cold Receptor Nerve Terminals

  • Richard W. Carr
  • James A. Brock
Chapter
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 508)

Abstract

The mechanisms of sensory transduction in the fine nerve terminals of free nerve endings supplied by AS and C sensory axons are largely a matter of speculation. This is because the nerve terminals are small and inaccessible, particularly in intact tissues like skin. However, some of the difficulties associated with investigating the physiology of fine nerve terminals have recently been overcome using an in vitro preparation of the guinea-pig cornea that allows nerve terminal impulses (NTIs) to be recorded extracellularly from single polyrnodal and cold receptor nerve terminals. For cold receptors, the rate of spontaneously occurring NTIs is increased during cooling and decreased during heating. In addition, heating and cooling differentially modulate the shape of the recorded NTI. At the same temperature, NTIs are larger in amplitude and faster in time course during heating than those during cooling. The differential effect of heating and cooling on NTI shape is not considered to result simply from the temperature dependence of voltage-activated conductance kinetics or activity dependent changes in membrane excitability. Instead, changes in NTI shape may reflect changes in nerve terminal membrane potential that underlie the process of thermal transduction.

Keywords

Nerve Terminal Membrane Excitability Sensory Axon Free Nerve Ending Cold Receptor 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Belmonte, C. Gallar, J. Pozo, M. A., and Rebello, I., 1991, Excitation by irritant chemical substances of sensory afferent units in the cat’s corneaJournal of Physiology437, 709–725.PubMedGoogle Scholar
  2. Belmonte, C. Garcia-Hirschfeld, J., and Gallar, J., 1997, Neurbiology of ocular painProgress in Retinal Eye Research16,117–156.CrossRefGoogle Scholar
  3. Brock, J. A. McLachlan, E., and Belmonte, C., 1998, Tetrodotoxin-resistant impulses in single nociceptor nerve terminals in guinea-pig corneaJournal of Physiology489, 389–402.Google Scholar
  4. Brock, J. A. Pianova, S., and Belmonte, C., 2001, Differences between nerve terminal impulses of polymodal nociceptors and cold sensory receptors of the guinea-pig corneaJournal of Physiology 533493–501.PubMedCrossRefGoogle Scholar
  5. Darian-Smith, I. Johnson, K. O., and Dykes, R., 1973, ‘Cold’ fiber population innervating palmar and digital skin of the monkeyJournal of Neurophysiology 36325–346.PubMedGoogle Scholar
  6. Dudel, J., 1963, Presynaptic inhibition of the excitatory nerve terminal in the neuromuscular junction of the crayfishPflügers Archives277, 537–557.CrossRefGoogle Scholar
  7. Gallar, J. Pozo, M. A. Tuckett, R. P., and Belmonte, C., 1993, Response of sensory units with unmyelinated fibres to mechanical, thermal and chemical stimulation of the cat’s corneaJournal of Physiology468, 609–622.PubMedGoogle Scholar
  8. Katz, B., and Miledi, R., 1965, Propagation of electrical activity in motor nerve terminalsProceedings of the Royal Society B161, 453–482.CrossRefGoogle Scholar
  9. Rang, H. P., and Ritchie, J. M., 1968, On the electrogenic sodium pump in mammalian non-nyelinated nerve fibres and its activation by various external cationsJournal of Physiology196, 183–221.PubMedGoogle Scholar
  10. Reid, G., and Flonta, M.-L., 2001, Cold current in thermoceptive neuronsNature413:480.PubMedCrossRefGoogle Scholar
  11. Reid, G., and Flonta, M.-L., 2001, Cold transduction by inhibition of a background potassium conductance in rat primary sensory neuronesNeuroscience Letters297, 171–174.PubMedCrossRefGoogle Scholar
  12. Smith, D.O., 1988, Determinants of nerve terminal excitability, in:Neurology and NeurobiologyP. W. Lanfield and S. A. Deadwyler, ed., Alan Liss Inc., New York, pp. 411–438.Google Scholar
  13. Whitear, M., 1960, An electron microscope study of the cornea in mice, with special reference to the innervationJournal of Anatomy94, 387–409.PubMedGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2002

Authors and Affiliations

  • Richard W. Carr
  • James A. Brock
    • 1
  1. 1.Prince of Wales Medical Research InstituteBarker St., RandwickSydneyAustralia

Personalised recommendations