Kinetics of D-glucose transport into renal membrane vesicles: measurements using a vacuum manifold apparatus

The rapid kinetics of D-glucose uptake into membrane vesicles, prepared from the renal cortex of the rat, were measured. A vacuum manifold apparatus for the filtration of suspensions containing membrane vesicles and radiolabelled sugars was constructed to permit measurements of D-glucose accumulation within the vesicles at 8-s intervals. The rate of Na+-independent accumulation of D-glucose was nearly constant for the first 24 s while the rate for Na+-dependent uptake was always changing. While a linear relationship between Na+-dependent D-glucose accumulation and time could not be established for a time period as short as 8 s, the time for half maximum Na+-dependent D-glucose uptake could be estimated. A value of 4 s for half maximum accumulation D-glucose into membrane vesicles in the presence of sodium was obtained.