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Glutamate‐Induced Increase in Intracellular Ca 2+ in Cerebral Cortex Neurons Is Transient in Immature Cells but Permanent in Mature Cells
Author(s) -
Wahl Philip,
Schousboe Arne,
Honoré Tage,
Drejer Jorgen
Publication year - 1989
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1989.tb07430.x
Subject(s) - glutamate receptor , nmda receptor , extracellular , cerebral cortex , biophysics , chemistry , antagonist , metabotropic glutamate receptor , intracellular , neuroscience , endocrinology , biology , medicine , biochemistry , receptor
The free cytosolic Ca 2+ concentration ([Ca 2+ ],) of cultured cerebral cortex neurons was determined using a fluorescent Ca 2+ chelator (Fluo‐3) after exposure of the neurons to glutamate. Mature neurons (8 days in culture) responded within 45 s to 100 μ M glutamate by an increase in [Ca 2+ ]j from 75 to 340 nM , an increase that during the following 6 min of exposure reached 400 nM. This increase in [Ca 2+ ]j could not be reversed by removal of glutamate. In the absence of extracellular CaCl 2 , only part of the initial, rapid, glutamate‐induced increase in [Ca 2+ ]j was observed in these neurons. In contrast to these findings, neurons cultured for only 2 days (immature neurons) exhibited only a small (from 75 to 173 nM ) increase in [Ca 2+ ]j after exposure to 100 μ M glutamate, and this rapid increase in [Ca 2+ ]j tended to decline on prolonged exposure to glutamate. Moreover, after removal of glutamate, the increase in [Ca 2+ ]j was fully reversible. Pharmacological characterization of the response to glutamate in mature neurons showed that the y N ‐methyl‐D‐aspartate (NMDA) receptor antagonists phencyclidine and D‐2‐amino‐5‐phosphonovalerate blocked 75 and 90%, respectively, of the response, whereas the non‐NMDA antagonist 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione had little effect.