Origin of intracellular Ca2+ elevation induced by in vitro ischemia-like condition in hippocampal slices.
Microfluorometry was used to investigate the origin of intracellular Ca2+ ([Ca2+]i) elevation in field CA1 of gerbil hippocampal slices perfused with a glucose-free physiological medium equilibrated with a 95% N2/5% CO2 gas mixture (standard in vitro ischemia-like condition). Large [Ca2+]i elevation was detected about 4 min after the beginning of standard in vitro ischemia-like condition, which was accompanied with a negative shift of extracellular DC potential. When slices were perfused with Ca(2+)-free in vitro ischemia-like medium, large [Ca2+]i elevation was observed about 3.5 min after the beginning of Ca(2+)-free in vitro ischemia-like condition, however, the increase in [Ca2+]i was more gradual and of a lesser extent compared with that detected in the slices perfused with the standard in vitro ischemia-like medium that contained Ca2+. When slices were perfused with the Ca(2+)-free in vitro ischemia-like medium that contained dantrolene (50 microM) which is known to prevent Ca(2+)-induced Ca2+ release from intracellular Ca2+ stores, the increase in [Ca2+]i was more gradual and of a lesser extent compared with that detected in the slices perfused with the Ca(2+)-free in vitro ischemia-like medium that did not contain dantrolene. These results indicate that large [Ca2+]i elevation induced by in vitro ischemia-like condition in field CA1 of the hippocampus was caused by both Ca2+ influx from extracellular space and Ca2+ release from intracellular Ca2+ stores, and that a part of the Ca2+ release was due to Ca(2+)-induced Ca2+ release from intracellular Ca2+ stores.
Mitani
A
A
Department of Physiology, School of Medicine, Ehime University, Japan.
Yanase
H
H
Sakai
K
K
Wake
Y
Y
Kataoka
K
K
D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D003620:Dantrolene / Q000494:pharmacology; D004558:Electric Stimulation; D004594:Electrophysiology; D005071:Evoked Potentials / Q000502:physiology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005456:Fluorescent Dyes; D005849:Gerbillinae; D006575:Heterocyclic Compounds, 3-Ring; D006624:Hippocampus / Q000378:metabolism*; D066298:In Vitro Techniques; D008027:Light; D008297:Male; D008856:Microscopy, Fluorescence; D009412:Nerve Fibers / Q000502:physiology; D013569:Synapses / Q000502:physiology
D005456:Fluorescent Dyes; D006575:Heterocyclic Compounds, 3-Ring; C068483:rhod-2; D003620:Dantrolene; D002118:Calcium