Changes in [Ca2+]0 during anoxia in CNS white matter

Neuroreport. 1998 Jun 22;9(9):1997-2000. doi: 10.1097/00001756-199806220-00015.

Abstract

Irreversible anoxic injury of axons in the rat optic nerve requires the presence of extracellular Ca2+. To test the hypothesis that Ca2+ enters an intracellular compartment during anoxia we monitored [Ca2+]0 in this CNS white matter tract using ion-sensitive microelectrodes. Periods of anoxia lasting 15 min resulted in a rapid, reversible increase in [Ca2+]0 accompanied by transient loss of nerve conduction. This increase in [Ca2+]0 was apparently the result of extracellular space shrinkage. Anoxic periods lasting 60 min resulted in an initial rise followed by a sustained fall in [Ca2+]0, indicative of net influx of Ca2+ into an intracellular compartment. Following reoxygenation after 60 min of anoxia, [Ca2+]0 slowly returned toward control levels but nerve conduction recovered incompletely, indicating irreversible loss of function. Removal of bath Ca2+ lowered [Ca2+]0 to about 100 microM, prevented the anoxia-induced fall in [Ca2+]0, and protected against irreversible loss of the compound action potential.

Publication types

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

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calibration
  • Central Nervous System / metabolism*
  • Electrophysiology
  • Hypoxia, Brain / metabolism*
  • Microelectrodes
  • Optic Nerve / metabolism
  • Rats

Substances

  • Calcium