Concanavalin A enhances quisqualate-induced calcium influx in cerebellar granule cells in culture.
In primary cultures of cerebellar granule cells kainate produced marked influx of 45Ca2+, partially sensitive to the N-methyl-D-aspartate (NMDA) antagonist, 3-(+/-)-2-carboxypiperazin-4-yl)- propyl-1-phosphonic acid (CPP), indicating involvement of an NMDA receptor-sensitive component that may be secondary to kainate-induced glutamate release. Sodium removal partially inhibited kainate's effect. Quisqualate also produced influx of 45Ca2+, but with lower efficacy and higher potency than kainate. This action of quisqualate was unaffected by CPP and by sodium removal. Preincubation of cells with the plant lectin concanavalin A (Con A), but not with its succinyl derivative, enhanced quisqualate-induced calcium influx, and to a lesser extent kainate's effect. Inclusion of quisqualate in preincubation medium antagonized Con A potentiation of quisqualate response. Also Con A was ineffective when included in the incubation medium only, without preincubation. Preincubation of rat brain cortical membranes with Con A but not with succinyl Con A increased the binding of the AMPA receptor agonist, [3H]alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid ([3H]AMPA). The results suggest that Con A enhancement of quisqualate response possibly involves the modification of an AMPA recognition site and requires preincubation in the absence of an agonist (here quisqualate).
Danysz
W
W
Department of Pharmacology, Merz+Co, Frankfurt/Main, Germany. (CompuServe):100631,454.
Raulli
R
R
Wroblewski
J T
JT
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D003208:Concanavalin A / Q000494:pharmacology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D016318:Quisqualic Acid / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013268:Stimulation, Chemical
D018690:Excitatory Amino Acid Agonists; D003208:Concanavalin A; D016318:Quisqualic Acid; D002118:Calcium