Study type: Medical/biological study (experimental study)

Sequential changes in cerebral blood flow, early neuropathological consequences and blood-brain barrier disruption following radiofrequency-induced localized hyperthermia in the rat med./bio.

By: Ohmoto Y, Fujisawa H, Ishikawa T, Koizumi H, Matsuda T, Ito H
Published in: Int J Hyperthermia 1996; 12 (3): 321-334
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Aim of study (acc. to author)

To study temperature distribution, early histological changes, blood-brain barrier disruption and sequential changes in cerebral blood flow following hyperthermia ranging from 37 to 45°C in a new rat model of radiofrequency-induced localized cerebral hyperthermia.

Background/further details

In this model, interstitial hyperthermia was induced by a new radiofrequency electrode.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 8 MHz
Exposure duration: 30 min
  • power: 10 W unspecified (unspecified) (20 W)

Exposure 1

Main characteristics
Frequency 8 MHz
Type
Exposure duration 30 min
Exposure setup
Exposure source
Setup Rats were placed in a prone position fixed in a stereotactic frame and electrodes were inserted 10 mm deep into the brain.
Parameters
Measurand Value Type Method Mass Remarks
power 10 W unspecified - unspecified 20 W

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

Significant histological changes and blood-brain barrier disruption were revealed in brain regions heated to 43°C and above. In the cortex heated to 41°C, the cerebral blood flow doubled 20 min after hyperthermia induction, and then returned to the pre-hyperthermic level. In the cortex heated to 43°C, the cerebral blood flow increased to 134% of the baseline level 10 min after hyperthermia induction, and then fell to reach its minimum level (31% of the baseline level). In the cortex heated to 45°C, the cerebral blood flow decreased immediately after hyperthermia induction to reach 10% of the baseline level.
The data suggest that hyperthermia-induced cellular injury in the central nervous system is associated with cerebral ischemia and the threshold temperature for such injury is 43°C. This model is useful for investigating the effects of hyperthermia on various cerebral functions.

Study character:

Study funded by

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