The difference in the effect of glutamate and NO synthase inhibitor on free calcium concentration and Na+, K+-ATPase activity in synaptosomes from various brain regions

The significant increase of free calcium concentration ([Ca2+]i) was found in rat cerebral cortex synaptosomes and hippocampal crude synaptosomal fraction after their exposure to glutamate. But no change of [Ca2+]i was revealed in cerebellar synaptosomes, the slight increase of [Ca2+]i in striatal s...

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Bibliographic Details
Published in:Neurochemical research 1999-09, Vol.24 (9), p.1101-1106
Main Authors: AVROVA, N. F, SHESTAK, K. I, ZAKHAROVA, I. O, SOKOLOVA, T. V, LEONT'EV, V. G
Format: Article
Language:English
Subjects:
Animals
Brain - enzymology
Brain - metabolism
Calcium - metabolism
Enzyme Inhibitors - pharmacology
Glutamic Acid - pharmacology
In Vitro Techniques
Male
NG-Nitroarginine Methyl Ester - pharmacology
Nitric Oxide Synthase - antagonists & inhibitors
Rats
Rats, Wistar
Sodium-Potassium-Exchanging ATPase - metabolism
Synaptosomes - enzymology
Synaptosomes - metabolism
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Summary:The significant increase of free calcium concentration ([Ca2+]i) was found in rat cerebral cortex synaptosomes and hippocampal crude synaptosomal fraction after their exposure to glutamate. But no change of [Ca2+]i was revealed in cerebellar synaptosomes, the slight increase of [Ca2+]i in striatal synaptosomes was not significant. The presence of Ng-nitro-L-arginine methyl ester (L-NAME) in the incubation medium practically prevented the increase of [Ca2+]i initiated by glutamate in cerebral cortex synaptosomes, but not in hippocampal ones. The significant diminution of [Ca2+]i in the presence of this inhibitor was shown in striatal synaptosomes exposed to glutamate. Na+,K+-ATPase activity is significantly lower in cerebral cortex, striatal and hippocampal synaptosomes exposed to glutamate. L-NAME prevented the inactivation of this enzyme by glutamate. In cerebellar synaptosomes the tendency to the decrease of enzymatic activity in the presence of L-NAME was on the contrary noticed. Thus, the data obtained provide evidence of the protective effect of NO synthase inhibitor in brain cortex and striatal synaptosomes, but not in cerebellar synaptosomes. Synaptosomes appear to be an adequate model to study the regional differences in the mechanism of toxic effect of excitatory amino acids.
ISSN:0364-3190
1573-6903
DOI:10.1023/A:1020752101736