Minimal effect of brain temperature changes on glutamate release in rat following severe global brain ischemia: a dialysis electrode study.
Using a dialysis electrode, we recently developed an oxygen-independent system for real-time measurement of the glutamate concentration in the extracellular space ([Glu]e) during ischemia. This system allows separate evaluation of intra-ischemic biphase [Glu]e elevation, i.e. release from synaptic vesicles (1st phase), reversed uptake of glutamate from metabolic pools in neuronal cells (2nd phase), and post-ischemic glutamate re-uptake in ischemia-reperfusion models. Using the system, we attempted to clarify the relationship between biphase glutamate release and brain temperature in a model of acute global ischemia produced by transecting both carotid arteries. Our results showed that, in contrast to mild hyperthermia, hypothermia did not inhibit the 1st phase of [Glu]e release, and changes in intra-ischemic brain temperature had a minimal effect on the 2nd phase of [Glu]e elevation during severe acute ischemia. These findings, together with our previous data, indicate that brain temperature change in the intra-ischemic period plays an important role in disturbance of the glutamate re-uptake system during ischemia.
Asai
S
S
Department of Pharmacology, Nihon University School of Medicine, Tokyo, Japan.
Zhao
H
H
Takahashi
Y
Y
Nagata
T
T
Kohno
T
T
Ishikawa
K
K
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D001921:Brain / Q000378:metabolism / Q000502:physiology*; D002545:Brain Ischemia / Q000378:metabolism / Q000503:physiopathology*; D004567:Electrodes, Implanted; D004569:Electroencephalography; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D051381:Rats; D011921:Rats, Inbred WKY
D018698:Glutamic Acid