Diffusion constants in the extracellular space of brain tissue

Abstract

A direct method for the estimation of the effective diffusion constants holding in the extracellular spaces of incubated slices of rat cerebral cortex or liver tissue slices is described. From the results obtained, it appears that Na ions, inulin and sucrose have diffusion constants in extracellular tissue spaces of the same order of magnitude as those for the respective substance in free solution. The diffusion constant for K ions in extracellular brain tissue spaces is much reduced, but this effect is not apparent in liver tissue. The slow diffusion may be a property of nervous tissue and may be a specific property of K ions.