Glutamate-induced increases in intracellular free Mg2+ in cultured cortical neurons.
Intracellular free Mg2+ concentrations ([Mg2+]i) in single rat brain neurons were measured with the Mg(2+)-sensitive fluorescent dye magfura-2. Addition of glutamate with glycine raised [Mg2+]i from 1 to more than 11 mM compared with the resting concentration of 0.5 mM, an effect mediated by N-methyl-D-aspartate receptors. Most of the increase in [Mg2+]i was independent of extracellular Mg2+, but was dependent on extracellular Ca2+. The second component of the increase induced by glutamate was independent of extracellular Ca2+, but required extracellular Mg2+ and was amplified by extracellular Na+ removal. These results indicate that regulation of [Mg2+]i by neurotransmitters such as glutamate may be important in controlling neuronal excitability.
Brocard
J B
JB
Département de Neurobiologie, Ecole Normale Supérieure, Paris, France.
Rajdev
S
S
Reynolds
I J
IJ
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000378:metabolism*; D004622:Embryo, Mammalian; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D005998:Glycine / Q000494:pharmacology; D007608:Kainic Acid / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism*; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D014701:Veratridine / Q000494:pharmacology
D005456:Fluorescent Dyes; D005971:Glutamates; D016194:Receptors, N-Methyl-D-Aspartate; C058776:2-(2-(5-carboxy)oxazole)-5-hydroxy-6-aminobenzofuran-N,N,O-triacetic acid; D018698:Glutamic Acid; D016202:N-Methylaspartate; D014701:Veratridine; D008274:Magnesium; D007608:Kainic Acid; D002118:Calcium; D005998:Glycine; D016257:Fura-2