Effects of brain temperature on CBF thresholds for extracellular glutamate release and reuptake in the striatum in a rat model of graded global ischemia.
We simultaneously measured extracellular glutamate ([Glu]e) elevation and local CBF using a real-time monitoring method and laser-Doppler flowmetry, respectively, in the rat striatum in a modified graded global ischemia model. Ischemic brain temperatures were kept at 32 degrees C, 37 degrees C and 39 degrees C. Three distinct types of intraischemic [Glu]e elevation, reflecting mild, moderate and massive glutamate release, were observed. Brain temperature plays an important role in determining CBF thresholds for each of the three types of [Glu]e elevation. CBF thresholds for [Glu]e elevations shifted to a lower level range as brain temperature was reduced. In mild or moderate ischemia, there is no exposure to sustained [Glu]e elevation, which is seen only in relatively severe ischemia characterized by biphasic [Glu]e elevation.
Zhao
H
H
Department of Pharmacology, Nihon University School of Medicine, Tokyo, Japan.
Asai
S
S
Kohno
T
T
Ishikawa
K
K
D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D001921:Brain / Q000098:blood supply / Q000378:metabolism; D002545:Brain Ischemia / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004195:Disease Models, Animal; D005110:Extracellular Space / Q000378:metabolism*; D005334:Fever / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D007035:Hypothermia / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D008839:Microelectrodes; D051381:Rats; D017208:Rats, Wistar
D018698:Glutamic Acid