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.

Blood↗

PubMed1960

Efflux of red cell water into buffered hypertonic solutions.

Buffered NaCl solutions hypertonic to rabbit serum were prepared and freezing point depressions of each determined after dilution with measured amounts of water. Freezing point depression of these dilutions was a linear function of the amount of water added. One ml. of rabbit red cells was added to each 4 ml. of the hypertonic solutions and after incubation at 38 degrees C. for 30 minutes the mixture was centrifuged and a freezing point depression determined on the supernatant fluid. The amount of water added to the hypertonic solutions by the red cells was calcuated from this freezing point depression. For each decrease in the freezing point of -0.093 degrees C. of the surrounding solution red cells gave up approximately 5 ml. of water per 100 ml. of red cells in the range of -0.560 to -0.930 degrees C. Beyond -0.930 degrees C. the amount of water given up by 100 ml. of red cells fits best a parabolic equation. The maximum of this equation occurred at a freezing point of the hypertonic solution of -2.001 degrees C. at which time the maximum amount of water leaving the red cells would be 39.9 ml. per 100 ml. of red cells. The data suggest that only about 43 per cent of the red cell water is available for exchange into solutions of increasing tonicity.

Buffers↗

PubMed1960

Efflux and influx of erythrocyte water.

Rabbit erythrocytes were washed in buffered NaCl solutions isotonic with rabbit serum (Delta(t) -0.558 degrees C.) and suspended in buffered NaCl solutions of tonicity equidistant from intracellular tonicity (Delta(t) = -0.558 degrees C. +/- 0.112 degrees C.) of varying pH and incubated at varying temperatures. After incubation, the freezing point depression (Delta(t)) was measured on the supernatant. Change in the Delta(t) measured change in the water content of the extracellular solutions-water being withdrawn by erythrocytes (W(I)) from the hypotonic solutions and added (W(E)) to the hypertonic solutions. W(E) was always less than W(I) and was inversely proportional to the pH in the range 6.5-8.0. W(E) was significantly increased by lowering the temperature of the cell suspension to 4 degrees C. W(I) was increased by raising or lowering the pH or raising the temperature of the cell suspension. W(E) x W(I) not equal k. W(E) and W(I) were affected differently by changes in pH and temperature. It was concluded that W(E) and W(E) were probably under different physicochemical control.

Erythrocytes↗

PubMed1960