Increases in [Ca2+]i and changes in intracellular pH during chemical anoxia in mouse neocortical neurons in primary culture

✍ Scribed by Nanna Koschmieder Jørgensen; Stine Falsig Petersen; Inge Damgaard; Arne Schousboe; Else Kay Hoffmann

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 148 KB
• Volume: 56
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/(sici)1097-4547(19990515)56:4<358::aid-jnr4>3.0.co;2-g

✦ Synopsis

The effect of chemical anoxia (azide) in the presence of glucose on the free intracellular Ca 2؉ concentration ([Ca 2؉ ] i ) and intracellular pH (pH i ) in mouse neocortical neurons was investigated using Fura-2 and BCECF. Anoxia induced a reversible increase in [Ca 2؉ ] i which was significantly inhibited in nominally Ca 2؉ -free medium. A change in pH o (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 [Ca 2؉ ] 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 pH i 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 Ca 2؉ -free medium, the initial acidification was followed by a significant alkalinization. At pH o 8.2, the alkalinization was significantly increased, while at pH o 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.