Effect of hypothermia on brain multi-parametric activities in normoxic and partially ischemic rats

Judith Sonn, Einat Granot, Revital Etziony, Avraham Mayevsky

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9 Scopus citations


Hypothermia, as well as anesthesia, are known to protect the brain against ischemia, hypoxia and other pathological damages. One of the mechanisms of this improvement could be by lowering brain function, and thereby lowering oxygen demand. We examined the effect of hypothermia on brain function and blood supply in awake and anesthetized rats and studied the interaction between partial ischemia and the responses to hypothermia. The brain function multiprobe (BFM) used enabled simultaneous measurements of cerebral blood flow (CBF), mitochondrial NADH redox state, extracellular K+ concentration, DC potential and ECoG from the cerebral cortex in rats whose brain temperature was lowered by 5°C. Hypothermia was induced in awake, anesthetized and brain ischemic-anesthetized rats. In anesthetized and ischemic-anesthetized rats, the time required for lowering the brain temperature by 5°C was five times less than in the normal awake animals. No significant changes in CBF and NADH levels were found in response to hypothermia in the awake animals. In contrast, a significant decrease in extracellular K+ concentration was recorded under hypothermia, probably due to the lower rate of depolarization. Hypothermia in anesthetized and in ischemic-anesthetized rats did not significantly affect the levels of mitochondrial NADH, CBF and extracellular K+. Hypothermia under ischemia was expected to be more effective.

Original languageEnglish
Pages (from-to)239-246
Number of pages8
JournalComparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology
Issue number1
StatePublished - May 2002

Bibliographical note

Funding Information:
This study was supported by the Health Sciences Research Fund, the Charles Krown Research Fund in the Faculty of Life Sciences, and the Research Authority, Bar-Ilan University, Israel.


  • Anesthesia
  • Cerebral blood flow
  • Extracellular potassium
  • Ionic homeostasis
  • Mild hypothermia
  • Mitochondrial NADH
  • Partial ischemia


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