Modulation of extracellular calcium and its functional implications

Fed Proc. 1980 Apr;39(5):1519-23.


Changes in [Ca2+]0 are known to affect axonal excitability and synaptic transmission. Ca2+ is also a major component of dendritic action potentials, and changes in [Ca2+]0 may therefore influence dendritic function. Use of the Ca2+-specific ion-selective microelectrode has shown that significant decreases in [Ca2+]0 occur in stimulated neuronal ensembles. Such changes are greatly enhanced during spreading depression and anoxia. The changes appear to be the result of Ca2+ entry into cells during activity, since the diffusion characteristics of Ca2+ in the extracellular space are not unusual. Decreases in [Ca2+]0 would lower the threshold for neuronal excitability but reduce synaptic transmission; rough numerical estimates of these effects are compiled. These are sufficiently large under some conditions to suggest, but not prove, possible modulatory effects of changes in [Ca2+]0. Variation in [Ca2+]0, however, is seen to be a valuable indicator of Ca2+-mediated processes in the nervous system.

Publication types

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

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Cerebellum / metabolism*
  • Cortical Spreading Depression
  • Diffusion
  • Extracellular Space / metabolism*
  • Fishes
  • Ischemic Attack, Transient / metabolism
  • Microelectrodes
  • Neurons / metabolism
  • Synaptic Transmission


  • Calcium