Calcium dynamics in neurons treated with toxic and non-toxic concentrations of glutamate.
Intracellular calcium concentration ([Ca2+]i) dynamics were simultaneously monitored in multiple cultured rat neurons loaded with Fluo-3 and continuously stimulated with glutamate (GLU). Three response types were observed: 10 microM GLU caused an initial transient increase in [Ca2+]i; 20 microM a biphasic response characterized by a 150-350 s 'calcium trough' between peaks; and 40 microM an initial sustained increase in [Ca2+]i. Neurons in calcium-free medium treated with 40 microM GLU showed only an initial transient increase in [Ca2+]i, demonstrating the dependence of sustained secondary increases in [Ca2+]i on extracellular calcium sources. We observed synchronized responses of multiple neurons within a given culture well, after GLU treatment, supporting the hypothesis that sustained influx of extracellular calcium may be stimulated by depletion of intracellular calcium and/or the release of endogenous excitatory amino acids.
Walter Reed Army Institute of Research, Department of Medical Neurosciences, Washington, DC 20307-5100.
M A
MA
DeCoster
M L
ML
Koenig
J C
JC
Hunter
F C
FC
Tortella
D000814:Aniline Compounds; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects*; D005456:Fluorescent Dyes; D005971:Glutamates / Q000633:toxicity*; D018698:Glutamic Acid; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D012016:Reference Values; D014966:Xanthenes
D000814:Aniline Compounds; D005456:Fluorescent Dyes; D005971:Glutamates; D014966:Xanthenes; C059715:Fluo-3; D018698:Glutamic Acid; D002118:Calcium