Extracellular and metabolic factors affecting the efflux and influx of erythrocyte water.

Water exchanges between rabbit erythrocytes and extracellular solutions equidistant from intracellular osmolarity were studied by freezing point depression techniques. Water efflux was always less than water influx and both were hypotonic to the intracellular and extracellular fluids. The magnitudes of these water exchanges were not dependent on the presence of extracellular cation. Stimulation of oxygen uptake by the addition of glucose and methylene blue increased water influx and, possibly, decreased water efflux. This could not be accounted for by accumulation of osmotically active intracellular metabolic products. O(2) uptake was markedly decreased during cellular dehydration, was slightly decreased during cellular overhydration, and was maximum at the water content of erythrocytes when suspended in a medium isotonic with plasma.