title: Alterations of glial cell function in temporal lobe epilepsy.
abstract: OBJECTIVE
  Comparison of extracellular K+ regulation in sclerotic and nonsclerotic epileptic hippocampus.
  
  
  METHODS
  Measurements of K+ signals with double-barreled K+-selective reference microelectrodes in area CAI of slices from human and rat hippocampus, induction of increases in extracellular potassium concentration by repetitive alvear stimulation or iontophoresis. and block of inward-rectifying and background K+ channels in astrocytes by barium.
  
  
  RESULTS
  In the CA1 pyramidal layer from normal rat hippocampus, barium augmented extracellular K+ accumulation induced by iontophoresis or antidromic stimulation in a dose-dependent manner. Similarly, barium augmented stimulus-induced K+ signals from nonsclerotic hippocampi (human mesial temporal lobe epilepsy). In contrast, barium failed to do so in sclerotic hippocampi (human mesial temporal lobe epilepsy, rat pilocarpine model).
  
  
  CONCLUSIONS
  Our findings suggest that in areas of reduced neuronal density (hippocampal sclerosis), glial cells adapt to permit rather large increases in extracellular potassium accumulation. Such increases might be involved in the transmission of activity through the sclerotic area.
authors.affiliation: Johannes Müller Institute of Physiology, Charité, Humboldt University of Berlin, Germany. uwe.heinemann@charite.de
authors.forename: U
authors.initials: U
authors.lastname: Heinemann
authors.forename: S
authors.initials: S
authors.lastname: Gabriel
authors.forename: R
authors.initials: R
authors.lastname: Jauch
authors.forename: K
authors.initials: K
authors.lastname: Schulze
authors.forename: A
authors.initials: A
authors.lastname: Kivi
authors.forename: A
authors.initials: A
authors.lastname: Eilers
authors.forename: R
authors.initials: R
authors.lastname: Kovacs
authors.forename: T N
authors.initials: TN
authors.lastname: Lehmann
mesh_terms: D000818:Animals; D001464:Barium / Q000494:pharmacology; D004833:Epilepsy, Temporal Lobe / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D005110:Extracellular Space / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D066298:In Vitro Techniques; D009457:Neuroglia / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D010862:Pilocarpine / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism / Q000502:physiology*; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D051381:Rats; D012598:Sclerosis
chemical_list: D010862:Pilocarpine; D001464:Barium; D011188:Potassium