Amplification of odor-induced Ca(2+) transients by store-operated Ca(2+) release and its role in olfactory signal transduction

J Neurophysiol. 2000 Jan;83(1):501-12. doi: 10.1152/jn.2000.83.1.501.


A critical role of Ca(2+) in vertebrate olfactory receptor neurons (ORNs) is to couple odor-induced excitation to intracellular feedback pathways that are responsible for the regulation of the sensitivity of the sense of smell, but the role of intracellular Ca(2+) stores in this process remains unclear. Using confocal Ca(2+) imaging and perforated patch recording, we show that salamander ORNs contain a releasable pool of Ca(2+) that can be discharged at rest by the SERCA inhibitor thapsigargin and the ryanodine receptor agonist caffeine. The Ca(2+) stores are spatially restricted; emptying produces compartmentalized Ca(2+) release and capacitative-like Ca(2+) entry in the dendrite and soma but not in the cilia, the site of odor transduction. We deplete the stores to show that odor stimulation causes store-dependent Ca(2+) mobilization. This odor-induced Ca(2+) release does not seem to be necessary for generation of an immediate electrophysiological response, nor does it contribute significantly to the Ca(2+) transients in the olfactory cilia. Rather, it is important for amplifying the magnitude and duration of Ca(2+) transients in the dendrite and soma and is thus necessary for the spread of an odor-induced Ca(2+) wave from the cilia to the soma. We show that this amplification process depends on Ca(2+)-induced Ca(2+) release. The results indicate that stimulation of ORNs with odorants can produce Ca(2+) mobilization from intracellular stores without an immediate effect on the receptor potential. Odor-induced, store-dependent Ca(2+) mobilization may be part of a feedback pathway by which information is transferred from the distal dendrite of an ORN to its soma.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Caffeine / pharmacology
  • Calcium / physiology*
  • Calcium-Binding Proteins / drug effects
  • Calcium-Binding Proteins / physiology*
  • Cilia / drug effects
  • Cilia / physiology*
  • Cyclohexanols*
  • Dendrites / drug effects
  • Dendrites / physiology
  • Egtazic Acid / pharmacology
  • Eucalyptol
  • In Vitro Techniques
  • Menthol / analogs & derivatives
  • Menthol / pharmacology
  • Models, Neurological
  • Monoterpenes*
  • Odorants*
  • Olfactory Pathways / physiology*
  • Olfactory Receptor Neurons / drug effects
  • Olfactory Receptor Neurons / physiology*
  • Patch-Clamp Techniques
  • Signal Transduction / physiology
  • Solvents
  • Terpenes*
  • Thapsigargin / pharmacology
  • Urodela


  • Calcium-Binding Proteins
  • Cyclohexanols
  • Monoterpenes
  • Solvents
  • Terpenes
  • Menthol
  • Caffeine
  • Egtazic Acid
  • Thapsigargin
  • Eucalyptol
  • Calcium