Effect of hyperthermia on glutamate release in ischemic penumbra after middle cerebral artery occlusion in rats

K. Takagi, M. D. Ginsberg, M. Y.T. Globus, E. Martinez, R. Busto

Research output: Contribution to journalArticle

93 Scopus citations

Abstract

Using microdialysis, we investigated the effect of hyperthermia on glutamate release in penumbral cortex of rats with 2 h of either normothermic (37°C) or hyperthermic (39°C) middle cerebral artery (MCA) occlusion. Penumbral blood flow (CBF) was measured by laser-Doppler flowmetry. CBF values (expressed as %preischemic values) in normothermic and hyperthermic groups were 24 ± 11 (SD) and 24 ± 16%, respectively, during ischemia and 102 ± 81 and 147 ± 79% during recirculation. Average extracellular glutamate in the hyperthermic group increased from a baseline of 7 ± 2 μM to a peak of 217 ± 184 μM at 10-20 min after onset of ischemia but returned to near baseline after 60 min. Glutamate in the normothermic group increased from 4 ± 2 μM to a peak of 26 ± 17 μM at 10-20 min after MCA occlusion but fell to near-baseline before recirculation. Thus reuptake systems appeared to remain functional in ischemic penumbra, even during hyperthermia. Ischemic glutamate release was significantly higher in hyperthermic than in normothermic rats: average values of individual rats' peak levels were 251 ± 221 μM and 37 ± 34 μM, respectively. The ischemic CBF threshold value for glutamate release was 33% of control in the normothermic group but 61% in the hyperthermic group.

Original languageEnglish (US)
Pages (from-to)H1770-H1776
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume267
Issue number5 36-5
DOIs
StatePublished - 1994

Keywords

  • brain temperature
  • cerebral blood flow
  • cerebral ischemia
  • neurotransmitters
  • penumbra

ASJC Scopus subject areas

  • Physiology
  • Agricultural and Biological Sciences(all)

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