The Glomerular Permeability Determined by Dextran Clearance Using Sephadex Gel Filtration

A method is described for measuring glomerular permeability by dextran clearance using Sephadex gel filtration technique. Clearance is shown to be a function of molecular size, decreasing with increasing molecular weight. At a mol. weight higher than 55,000, the clearance is very low and approximately zero, while it averages 95 ml per minute at a mol. weight of 15,000. If plotted in a log.log. graph, a linear relation is found between clearance and molecular weight. In a semilog. graph, however, with clearance plotted against log. Stokes radius, the relation is also linear, with a slight deflection in the high molecular part, however.