Extracellular accumulation of glutamate in the hippocampus induced by ischemia is not calcium dependent--in vitro and in vivo evidence.
Calcium dependency of ischemia-induced increase in extracellular glutamate in the hippocampus was studied in vitro and in vivo. Perfusion of a low pO2 medium without glucose (in vitro ischemia) induced an increase in extracellular glutamate in rat hippocampal slices. This increase did not depend on Ca2+, which is in contrast with the observation that about 40% of membrane depolarization (50 mM KCl)-evoked release was Ca2+-dependent. In vivo cerebral ischemia of 5 min duration in gerbils also caused Ca2+-independent increase in extracellular glutamate in the hippocampus. The data suggest that the increase in extracellular glutamate induced by ischemia is not due to the enhanced release of neurotransmitter glutamate.
Ikeda
M
M
Tsukuba Research Laboratories, Eisai Co., Ltd., Ibaraki, Japan.
Nakazawa
T
T
Abe
K
K
Kaneko
T
T
Yamatsu
K
K
D000818:Animals; D002118:Calcium / Q000502:physiology*; D005110:Extracellular Space / Q000378:metabolism*; D005849:Gerbillinae; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D006624:Hippocampus / Q000378:metabolism* / Q000503:physiopathology; D066298:In Vitro Techniques; D002546:Ischemic Attack, Transient / Q000378:metabolism*; D008297:Male; D010101:Oxygen Consumption; D011188:Potassium / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D005971:Glutamates; D018698:Glutamic Acid; D011188:Potassium; D002118:Calcium