Potentiation of nicotinic receptor response by external calcium in rat central neurons

Neuron. 1992 May;8(5):937-45. doi: 10.1016/0896-6273(92)90208-u.


Nicotinic acetylcholine receptor (nAChR) responses of rat medial habenular neurons are potentiated up to 3.5-fold by increasing the concentration of external Ca2+ in the millimolar range. This effect, independent of voltage, is probably due to the binding of Ca2+ to an external site. External Ca2+ decreases nAChR single-channel conductance at negative but not positive potentials, and it markedly enhances the frequency of opening of acetylcholine activated channels. The potentiating effect of Ca2+ is mimicked by Ba2+ and Sr2+, but barely by Mg2+. These data support the existence of positively acting allosteric sites for Ca2+, distinct from those involved in the decrease of single-channel conductance. A model in which external Ca2+ changes the properties of activation of the nAChR appears consistent with these data.

Publication types

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

MeSH terms

  • Allosteric Site
  • Animals
  • Barium / pharmacology
  • Brain / drug effects
  • Brain / physiology*
  • Calcium / pharmacology*
  • Cations, Divalent
  • Electric Conductivity
  • Kinetics
  • Neurons / drug effects
  • Neurons / physiology*
  • Rats
  • Rats, Inbred Strains
  • Receptors, Nicotinic / drug effects
  • Receptors, Nicotinic / physiology*
  • Strontium / pharmacology


  • Cations, Divalent
  • Receptors, Nicotinic
  • Barium
  • Calcium
  • Strontium