Changes of electrical impedance in edematous cat brain during hypoxia and after intracerebral ouabain injection

Abstract

Using an alternating current of 750 Hz, electrical impedance was measured at various depths in the white matter of the brain of cats previously subjected to a freezing injury of the cerebral cortex. The cold-induced brain edema resulted in a decrease of the impedance corresponding to an enlargement of the tissue extracellular space in which the edema fluid accumulated. Subsequent induction of hypoxia or intracerebral injection of ouabain resulted in an increase of the impedance; the increase was considered to be caused by a reduction of the extracellular space as fluid was shifted into the cellular elements.