Evidence that olfactory sensitivities to calcium and sodium are mediated by different mechanisms in the goldfish Carassius auratus

Neurosci Lett. 2007 Feb 27;414(1):90-3. doi: 10.1016/j.neulet.2006.12.007. Epub 2006 Dec 28.

Abstract

The current study investigated whether the olfactory sensitivity to Ca2+ and Na+ is mediated by the same mechanism in the goldfish, a freshwater teleost. The olfactory responses, as assessed by recording the electro-encephalogram (EEG) from the olfactory bulb, to changes in external [Ca2+] and to [Na+] were recorded in the absence and presence of increasing concentrations of the other ion. Low concentrations of Na+ (0-1.0mM) had no significant effects on the olfactory response to changes in [Ca2+] in terms of EC50, Imax or Hill co-efficient (n=8). A relatively high concentration of Na+ (10mM) significantly reduced the Imax and increased the EC50. One hundred millimolars Na+ reduced the olfactory response to Ca2+ to undetectable levels. Conversely, low concentrations of Ca2+ (0.1 and 1.0mM) significantly attenuated the olfactory response to changes in environmental [Na+], reducing the amplitude of response and increasing the threshold of detection (n=7). However, a high concentration of Ca2+ (10mM) failed to attenuate the olfactory response to Na+ completely. Taken together, these results suggest that, at normal environmental concentrations of these ions, Ca2+ and Na+ are detected by distinct and separate cellular mechanisms. However, there seems to be a degree of overlap between the two mechanisms. The exact mechanisms involved, and their biological roles, remain to be established.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Action Potentials / physiology
  • Animals
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Dose-Response Relationship, Drug
  • Electroencephalography / drug effects
  • Goldfish / physiology*
  • Neurons, Afferent / drug effects
  • Neurons, Afferent / physiology
  • Olfactory Bulb / drug effects
  • Olfactory Bulb / metabolism*
  • Olfactory Mucosa / drug effects
  • Olfactory Mucosa / metabolism*
  • Olfactory Nerve / drug effects
  • Olfactory Nerve / metabolism*
  • Sensory Thresholds / drug effects
  • Sensory Thresholds / physiology
  • Smell / drug effects
  • Smell / physiology*
  • Sodium / metabolism*
  • Sodium / pharmacology

Substances

  • Sodium
  • Calcium