The glomerular filterability of polyfructosan-S in immature infants.

Gel chromatography was performed on 21 plasma, 5 urine and 3 spinal fluid samples from pre-term infants who had received intravenous polyfructosan-S (PF-S), in order to investigate whether all sizes of PF-S molecule are filtered at the glomerulus and penetrate deep extra-cellular fluid compartments. Plasma obtained after 24 h continuous infusion of PF-S had identical chromatograms to the aqueous solution, suggesting no glomerular hold-up of the largest molecules. PF-S had a broader chromatogram than inulin, suggesting that it has larger molecules. Urine and plasma samples obtained early after a single injection had an excess of high molecular weight polyfructoside, suggesting that small molecules penetrate deep extracellular fluid compartments more easily. Spinal fluid samples had an excess of low molecular weight polyfructoside, suggesting slow penetration of the largest molecules.