ISSN:
1573-6903
Keywords:
Cerebellar granule cells
;
cortical astrocytes
;
excitatory amino acid
;
binding
;
glutamate receptor subtypes
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Membranes prepared from cerebellar granule cells and cortical astrocytes exhibited specific, saturable binding ofl-[3H]glutamate. The apparent binding constant K d was 135 nM and 393 nM and the maximal binding capacity Bmax 42 and 34 μmol/kg in granule cells and astrocytes, respectively. In granule cells the binding was strongly inhibited by the glutamate receptor agonists kainate, quisqualate, N-methyl-d-aspartate (NMDA),l-homocysteate and ibotenate, and the antagonistdl-5-aminophosphonovalerate. In astrocytes, only quisqualate among these was effective.l-Aspartate,l-cysteate,l-cysteinesulphinate and γ-d-glutamylglycine were inhibitors in both cell types. The binding was totally displaced in both cell types byl-cysteinesulphinate with IC50 in the micromolar range. In astrocytes the binding was also totally displaced by quisqualate, but in granule cells only partially by NMDA, kainate and quisqualate in turn. It is concluded from the relative potencies of agonists and antagonists in [3H]glutamate binding that cerebellar granule cells express the NMDA, kainate and quisqualate types of the glutamate receptor, while only the quisqualate-sensitive binding seems to be present in cortical astrocytes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00966803
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