N-methyl-D-aspartate responses in rat cerebellar granule cells are modified by chronic depolarisation in culture.
Following culture in high (25 mM) K+ conditions cerebellar granule cells only respond with a rise in cytosolic free calcium concentration ([Ca2+]i after removal of external Mg2+. When granule cells are grown in low (5 mM) K+ N-methyl-D-aspartate (NMDA) exerts a neurotrophic effect. We show that at the critical time for this effect NMDA will elicit a rise in [Ca2+]i in 5 mM K+ cultures even in the presence of Mg2+ and that growth in 25 mM K+ induces the rapid appearance of a Mg2+ block of NMDA receptors in granule cells. This suggests firstly, that a rise in [Ca2+]i could be involved in the neurotrophic effect of NMDA and secondly, that the characteristics of the NMDA responses in granule cells are modified as a result of growth under depolarising conditions.
Pearson
H
H
Department of Physiology, University of Liverpool, UK.
Graham
M E
ME
Burgoyne
R D
RD
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects*; D006098:Granulocytes / Q000187:drug effects*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D016202:N-Methylaspartate; D008274:Magnesium; D011188:Potassium; D002118:Calcium