Changes in extracellular calcium concentration in the immature rat cerebral cortex during anoxia are not influenced by MK-801.
The extracellular calcium concentration ([Ca2+]ec) was recorded by calcium-sensitive microelectrodes in the parietal cortex of 9-11 day old rats during anoxia. During the first 10 min of anoxia, [Ca2+]ec increased from 1.1 mM to 1.5 +/- 0.23 mM, and thereafter it started to decrease reaching below basal level after around 13 min. The [Ca2+]ec decrease was either slow and continuous, or biphased with a rapid initial decrease followed by a continuous slow decrease. After 60 min of anoxia, the [Ca2+]ec had reached 0.2-0.3 mM. Changes in [Ca2+]ec in animals treated with the NMDA receptor antagonist MK-801 (0.3 mg/kg i.p.) did not display any significant differences compared to controls. Thus, the strong neuroprotective effect of MK-801 in ischemic situations in the immature brain can not be explained by a prevention of calcium entry during anoxic depolarization.
Puka-Sundvall
M
M
Department of Anatomy and Cell Biology, University of Göteborg, Sweden.
Hagberg
H
H
Andiné
P
P
D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism*; D016291:Dizocilpine Maleate / Q000494:pharmacology*; D005110:Extracellular Space / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D009994:Osmolar Concentration; D051381:Rats; D017207:Rats, Sprague-Dawley
D016291:Dizocilpine Maleate; D002118:Calcium