Calcium signalling and regulation in olfactory neurons

Curr Opin Neurobiol. 1999 Aug;9(4):419-26. doi: 10.1016/S0959-4388(99)80063-4.


The odorant-induced Ca(2+) increase inside the cilia of vertebrate olfactory sensory neurons controls both excitation and adaptation. The increase in the internal concentration of Ca(2+) in the cilia has recently been visualized directly and has been attributed to Ca(2+) entry through cAMP-gated channels. These recent results have made it possible to further characterize Ca(2+)'s activities in olfactory neurons. Ca(2+) exerts its excitatory role by directly activating Cl(-) channels. Given the unusually high concentration of ciliary Cl(-), Ca(2+)'s activation of Cl(-) channels causes an efflux of Cl(-) from the cilia, contributing high-gain and low-noise amplification to the olfactory neuron depolarization. Moreover, in combination with calmodulin, Ca(2+) mediates odorant adaptation by desensitizing cAMP-gated channels. The restoration of the Ca(2+) concentration to basal levels occurs via a Na(+)/Ca(2+) exchanger, which extrudes Ca(2+) from the olfactory cilia.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Calcium / physiology*
  • Chloride Channels / physiology*
  • Cyclic AMP / physiology*
  • Humans
  • Olfactory Receptor Neurons / physiology*
  • Receptors, Odorant / physiology
  • Signal Transduction / physiology*


  • Chloride Channels
  • Receptors, Odorant
  • Cyclic AMP
  • Calcium