title: Increases in [Ca2+]i and changes in intracellular pH during chemical anoxia in mouse neocortical neurons in primary culture.
abstract: The effect of chemical anoxia (azide) in the presence of glucose on the free intracellular Ca2+ concentration ([Ca2+]i) and intracellular pH (pHi) in mouse neocortical neurons was investigated using Fura-2 and BCECF. Anoxia induced a reversible increase in [Ca2+]i which was significantly inhibited in nominally Ca2+-free medium. A change in pHo (8.2 or 6.6), or addition of NMDA and non-NMDA receptor antagonists (D-AP5 and CNQX) in combination, significantly reduced the increase in [Ca2+]i, pointing to a protective effect of extracellular alkalosis or acidosis, and involvement of excitatory amino acids. An initial anoxia-induced acidification was observed under all experimental conditions. In the control situation, this acidification was followed by a recovery/alkalinization of pHi in about 50% of the cells, a few cells showed no recovery, and some showed further acidification. EIPA, an inhibitor of Na+/H+ exchangers, prevented alkalinization, pointing towards anoxia-induced activation of a Na+/H+ exchanger. In a nominally Ca2+-free medium, the initial acidification was followed by a significant alkalinization. At pHo 8.2, the alkalinization was significantly increased, while at pHo 6.2, the initial acidification was followed by further acidification in about 50% of the cells, and by no further change in the remaining cells.
authors.affiliation: Biochemical Department, The August Krogh Institute, Copenhagen, Denmark. nkjorgensen@yahoo.com
authors.forename: N K
authors.initials: NK
authors.lastname: Jørgensen
authors.forename: S F
authors.initials: SF
authors.lastname: Petersen
authors.forename: I
authors.initials: I
authors.lastname: Damgaard
authors.forename: A
authors.initials: A
authors.lastname: Schousboe
authors.forename: E K
authors.initials: EK
authors.lastname: Hoffmann
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia / Q000502:physiology*; D002478:Cells, Cultured; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005452:Fluoresceins; D016257:Fura-2; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008815:Mice, Inbred Strains; D019579:Neocortex / Q000166:cytology / Q000187:drug effects / Q000196:embryology / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019810:Sodium Azide / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors / Q000502:physiology
chemical_list: D018691:Excitatory Amino Acid Antagonists; D005452:Fluoresceins; D017923:Sodium-Hydrogen Exchangers; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015763:2-Amino-5-phosphonovalerate; D000584:Amiloride; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D019810:Sodium Azide; D005947:Glucose; D002118:Calcium; D016257:Fura-2; C039614:ethylisopropylamiloride