Uptake of inulin by cells in rat brain cortex

Light and electron microscope autoradiography indicated that 3H-labelled inulin was taken up by neurons and glia cells of rat brain cortex in vitro. The mechanism, by which inulin passed the cell membranes, was studied by comparing the transport of inulin (molecular weight 5000) with the transport of dextran (molecular weight 75000). The half-time for the cellular in- and efflux for the two molecules was the same although their diffusion coefficients differed by a factor of 4-5. The transport mechanism was therefore interpreted as bulk transport, and vesicular transport is suggested. Efflux of inulin from brain cortex exposed to inulin in vivo indicated that cellular uptake of inulin also occurred in vivo.