Reduced voltage-dependent Ca2+ signaling in CA1 neurons after brief ischemia in gerbils

J Neurophysiol. 1999 Jan;81(1):299-306. doi: 10.1152/jn.1999.81.1.299.

Abstract

An initial overload of intracellular Ca2+ plays a critical role in the delayed death of hippocampal CA1 neurons that die a few days after transient ischemia. Without direct evidence, the prevailing hypothesis has been that Ca2+ overload may recur until cell death. Here, we report the first measurements of intracellular Ca2+ in living CA1 neurons within brain slices prepared 1, 2, and 3 days after transient (5 min) ischemia. With no sign of ongoing Ca2+ overload, voltage-dependent Ca2+ transients were actually reduced after 2-3 days of reperfusion. Resting Ca2+ levels and recovery rate after loading were similar to neurons receiving no ischemic insult. The tetrodotoxin-insensitive Ca spike, normally generated by these neurons, was absent at 2 days postischemia, as was a large fraction of Ca2+-dependent spike train adaptation. These surprising findings may lead to a new perspective on delayed neuronal death and intervention.

Publication types

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

MeSH terms

  • Action Potentials / drug effects
  • Animals
  • Brain Ischemia / physiopathology*
  • Calcium / metabolism
  • Calcium Channels / drug effects
  • Calcium Channels / physiology
  • Calcium Signaling / physiology*
  • Cerebrovascular Circulation / physiology
  • Electric Stimulation
  • Electrophysiology
  • Fluorescent Dyes
  • Fura-2
  • Gerbillinae
  • Ion Channel Gating / drug effects
  • Ischemic Preconditioning*
  • Male
  • Microelectrodes
  • Neurons / physiology*

Substances

  • Calcium Channels
  • Fluorescent Dyes
  • Calcium
  • Fura-2