Measurement of the Water Permeability of Single Human Granulocytes on a Microscopic Stopped-Flow Mixing System

The water permeability (L_p) of human granulocytes was measured for individual isolated cells with a novel, microscopic stopped-flow mixing system. Changes in volume were monitored as a cell was introduced suddently into an osmotically active solution. Permeability values were determined as a function of solution osmolality from the volume versus time curves for mixing into both hypotonic and hypertonic solutions within the range of 145 to 833 mOsm. The calculated reference permeability at 25°C was 1.15 μm/atm·min with an osmotic coefficient of 0.46 Osm/kg.