Odorant-regulated Ca2+ gradients in rat olfactory neurons

J Gen Physiol. 1993 Nov;102(5):907-24. doi: 10.1085/jgp.102.5.907.

Abstract

Olfactory neurons respond to odors with a change in conductance that mediates an influx of cations including Ca2+. The concomitant increase in [Cai] has been postulated to play a role in the adaptation to maintained odorant stimulation (Kurahashi, T., and T. Shibuya. 1990. Brain Research. 515:261-268. Kramer, R. H., and S. A. Siegelbaum. 1992. Neuron. 9:897-906. Zufall, F., G. M. Shepherd, and S. Firestein. 1991. Proceedings of the Royal Society of London, B. 246:225-230.) We have imaged the distribution of [Cai] in rat olfactory neurons (RON) using the Ca2+ indicator fura-2. A large percentage of the RON (42%, n = 35) responded to odorants with an increase in [Cai]. About half of the responding neurons displayed an increase in [Cai] at the apical end of the cell, but not at the soma. Moreover, in those cells that responded to odors with a standing [Cai] gradient, the gradient could be maintained for long periods of time (minutes) provided that the cells were continuously stimulated. In contrast, K(+)-induced depolarization elicited a more homogeneous increase in [Cai]. The spatially inhomogeneous increase in [Cai] elicited by odorants in some cells has important implications for the role of Ca2+ in adaptation because channels and enzymes regulated by Ca2+ will be affected differently depending on their location.

Publication types

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

MeSH terms

  • Animals
  • Biological Transport / physiology
  • Calcium / analysis*
  • Calcium / pharmacokinetics
  • Calcium / pharmacology
  • Calcium Channels / analysis
  • Calcium Channels / physiology*
  • Colforsin / pharmacology
  • Fura-2
  • Neurons, Afferent / chemistry
  • Neurons, Afferent / physiology
  • Odorants*
  • Olfactory Nerve / chemistry*
  • Olfactory Nerve / physiology*
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Odorant / analysis
  • Receptors, Odorant / physiology

Substances

  • Calcium Channels
  • Receptors, Odorant
  • Colforsin
  • Calcium
  • Fura-2