Glutamate-induced intracellular acidification of cultured hippocampal neurons demonstrates altered energy metabolism resulting from Ca2+ loads

J Neurophysiol. 1994 Dec;72(6):2563-9. doi: 10.1152/jn.1994.72.6.2563.

Abstract

1. Glutamate-evoked increases in intracellular free H+ concentration ([H+]i) were recorded from single rat hippocampal neurons grown in primary culture with carboxy SNARF-based dual emission microfluorimetry. The possibility that this acidification resulted from altered energy metabolism was investigated. 2. The response to 10 microM glutamate (delta pH = 0.41 +/- 0.14, mean +/- SD) was blocked by the N-methyl-D-aspartate (NMDA) receptor antagonist CGS19755 (10 microM) and required extracellular Ca2+. 3. Substituting the metabolic inhibitor 2-deoxyglucose for glucose in the extracellular buffer prevented glutamate-induced acidification. 4. Ba2+, which carries charge through Ca2+ channels, including the Ca2+ uniporter on the inner mitochondrial membrane, substituted for Ca2+ in mediating glutamate-induced cytoplasmic acidification. 5. Microinjection of ruthenium red, a compound that blocks mitochondrial Ca2+ sequestration, significantly inhibited glutamate-induced acidification. 6. The mitochondrial uncoupler, carbonyl cyanide-p-trifluoromethoxyphenyl-hydrazone (FCCP, 0.1 microM), mimicked and partially occluded the glutamate-induced [H+]i increase. 7. These findings indicate that glutamate-induced Ca2+ loads are sequestered by mitochondria, uncouple respiration, and produce metabolic acidosis. The glutamate-induced acidification is symptomatic of metabolic stress and may indicate that mitochondria play an important role in glutamate-induced neuronal death.

Publication types

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

MeSH terms

  • Animals
  • Barium / pharmacology
  • Calcium / metabolism
  • Calcium / physiology*
  • Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / pharmacology
  • Cells, Cultured
  • Deoxyglucose / metabolism
  • Energy Metabolism / drug effects*
  • Glutamic Acid / pharmacology*
  • Hippocampus / cytology
  • Hippocampus / drug effects
  • Hippocampus / metabolism*
  • Hydrogen-Ion Concentration
  • Microinjections
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Neurons / drug effects
  • Neurons / metabolism*
  • Pipecolic Acids / pharmacology
  • Rats
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors
  • Receptors, N-Methyl-D-Aspartate / metabolism

Substances

  • Pipecolic Acids
  • Receptors, N-Methyl-D-Aspartate
  • Barium
  • Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
  • Glutamic Acid
  • selfotel
  • Deoxyglucose
  • Calcium