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Calcium‐Sensitive Fluorescent Dyes Can Report Increases in Intracellular Free Zinc Concentration in Cultured Forebrain Neurons
Author(s) -
Cheng Chialin,
Reynolds Ian J.
Publication year - 1998
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 - 10.1046/j.1471-4159.1998.71062401.x
Subject(s) - postsynaptic potential , extracellular , biophysics , chemistry , intracellular , nmda receptor , zinc , glutamate receptor , excitatory postsynaptic potential , calcium , fura 2 , agonist , ethylenediamine , biochemistry , receptor , inorganic chemistry , biology , cytosol , organic chemistry , enzyme
High concentrations of Zn 2+ are found in presynaptic terminals of excitatory neurons in the CNS. Zn 2+ can be released during synaptic activity and modulate postsynaptic receptors, but little is known about the possibility that Zn 2+ may enter postsynaptic cells and produce dynamic changes in the intracellular Zn 2+ concentration ([Zn 2+ ] i ). We used fura‐2 and magfura‐2 to detect the consequences of Zn 2+ influx in cultured neurons under conditions that restrict changes in intracellular Ca 2+ and Mg 2+ concentrations. The resulting ratio changes for both dyes were reversed completely by the Zn 2+ chelator, N,N,N′,N′ ‐tetrakis(2‐pyridylmethyl)ethylenediamine, indicating that these dyes are measuring changes in [Zn 2+ ] i . We found that fura‐2 was useful in measuring small increases in [Zn 2+ ] i associated with exposure to Zn 2+ alone that may be mediated by a Na + /Ca 2+ exchanger. Magfura‐2, which has a lower affinity for Zn 2+ , was more useful in measuring larger agonist‐stimulated increases in [Zn 2+ ] i . The coapplication of 300 µ M Zn 2+ and 100 µ M glutamate/10 µ M glycine resulted in a [Zn 2+ ] i increase that was ∼40–100 n M in magnitude and could be inhibited by the NMDA receptor antagonist, MK‐801 (30 µ M ), or extracellular Na + . This suggests that Zn 2+ influx can occur through at least two different pathways, leading to varying increases in [Zn 2+ ] i . These findings demonstrate the feasibility of measuring changes in [Zn 2+ ] i in neurons.