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Excitatory Amino Acid Receptors and Depolarization‐Induced Ca 2+ Influx into Hippocampal Slices
Author(s) -
Crowder J. M.,
Croucher M. J.,
Bradford H. F.,
Collins J. F.
Publication year - 1987
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.1471-4159.1987.tb05756.x
Subject(s) - excitatory postsynaptic potential , nmda receptor , glutamate receptor , kainate receptor , chemistry , excitatory amino acid antagonists , quisqualic acid , amino acid , depolarization , veratridine , 2 amino 5 phosphonovalerate , biochemistry , biophysics , receptor , biology , kainic acid , ampa receptor , sodium , organic chemistry , sodium channel
Hippocampal brain slices were incubated with depolarizing agents or excitatory amino acids either alone or in the presence of excitatory amino acid antagonists [ω‐phosphonic α‐aminocarboxylic acids—2‐amino‐4‐phosphonobutyric acid (AP4), 2‐amino‐5‐phosphonovaleric acid (AP5), or 2‐amino‐7‐phosphonoheptanoic acid (AP7)—or γ‐D‐glutamylaminomethylsulphonic acid (GAMS)] or a calcium‐channel blocker, ( S )‐1‐(3‐methoxyphenyl)‐3‐methylaza‐7‐cyano‐7‐ (3,4‐dimethoxyphenyl)‐8‐methyl‐nonane hydrochloride [(‐)‐D888]. The uptake of 45 Ca 2+ and the efflux of glutamate or aspartate induced by veratrine or high K + was blocked (54–76%) by AP7 (IC 50 46–250 μ M ). AP5 and AP4 were less effective. (‐)‐D888 (10 μ M ) caused 100% block of evoked 45 Ca 2+ uptake. Uptake of 45 Ca 2+ induced by exogenous glutamate, aspartate, and N ‐methyl‐D‐aspartate (NMDA) was also inhibited by AP7, whereas GAMS completely blocked the action of kainate and partially blocked that of glutamate. The action of NMDA in stimulating 45 Ca 2+ uptake was Mg 2+ ‐sensitive, low Mg 2+ levels in the incubation medium selectively enhancing the response. It is concluded that Ca 2+ uptake evoked by excitatory amino acids is receptor‐mediated, and that released excitatory amino acids are responsible for a large part of the action of veratrine and high K + in stimulating 45 Ca 2+ uptake.