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Ionic and acid‐base regulation of neurons and glia during seizures
Author(s) -
Woodbury Dixon M.,
Engstrom Fae L.,
White H. Steve,
Chen C. F.,
Kemp J. W.,
Chow S. Y.
Publication year - 1984
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410160720
Subject(s) - bicarbonate , chemistry , neuroglia , acetazolamide , carbonic anhydrase , astrocyte , medicine , endocrinology , biophysics , biochemistry , biology , central nervous system , enzyme
Much evidence shows that glia regulates the cation and anion content of brain interstitial space. In rats the pH and bicarbonate (HCO 3 − ) concentration of neurons and glia were derived from carbon 14‐labeled HCO 3 − and dimethyloxazolidinedione uptake into brain and cerebrospinal fluid. Acetazolamide increases the total CO 2 concentration in neurons and decreases the pH and HCO 3 − concentration in glia. Inhibition of glial carbonic anhydrase (CA) reduces conversion of neuronally derived CO 2 to HCO 3 − glial pH is lowered, and neuronal CO 2 accumulates. CA therefore has an essential role in regulating pH in neurons, glia, and interstitial fluid. In audiogenic seizure mice, glial CA activity is increased and glial anion transport is reduced. As the mice age, seizure susceptibility, the increased CA activity, and the defect in anion transport disappear concurrently. The enhanced CA activity in the glial cells of these mice is an adaptive mechanism to overcome the defect in anion transport that results from a deficiency of HCO 3 − ‐dependent and Na + ‐and K + ‐dependent adenosine triphosphatase. Pentylenetetrazol stimulates neurons in neonatal rats, but after 10 days of age, when glia is present, it too is stimulated and the seizures are attenuated. Cobalt implantation in the cortex of rats also induces a glial response that ameliorates the focal seizures produced by this procedure.