Concordance between morphological and biochemical estimates of fluid spaces in rat brain cortex slices.

Abstract

A comparison was made between morphological and biochemical estimates of extracellular and intracellular fluid spaces in rat brain cortex slices incubated under different conditions. By light microscopy the periphery of the slices was found to be more swollen than the center; this regional difference was verified biochemically in unfixed tissue. The electronmicroscopic evaluation of intra- and extracellular fluid spaces was accordingly based upon findings in a preselected area. Due to intracellular penetration of inulin in rat brain cortex slices the biochemically, determined extracellular and intracellular spaces were obtained by compartmental analysis of the inulin space. The concordance between the biochemical and the morphological findings was good: Both methods showed that the extracellular space increased during the incubation to a considerable magnitude after one hr. and that this extracellular space was reduced by excess potassium, glutamate, anoxia or incubation at 0°. Under the same conditions the biochemically determined intracellular space was increased. This cellular swelling was confirmed morphologically and found to comprise mainly glia cells after exposure to excess potassium, predominantly neurons after incubation at 0° and both cell types after anoxia or addition of glutamate.