Electrophysiology of Corneal Cold Receptor Nerve Terminals
- 758 Downloads
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.
KeywordsNerve Terminal Membrane Excitability Sensory Axon Free Nerve Ending Cold Receptor
Unable to display preview. Download preview PDF.
- 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
- 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