Efflux and Influx of Erythrocyte Water

Rabbit erythrocytes were washed in buffered NaCl solutions isotonic with rabbit serum (Δ(t) -0.558°C.) and suspended in buffered NaCl solutions of tonicity equidistant from intracellular tonicity (Δ(t) = -0.558°C. ± 0.112°C.) of varying pH and incubated at varying temperatures. After incubation, the freezing point depression (Δ(t)) was measured on the supernatant. Change in the Δ(t) measured change in the water content of the extracellular solutions—water being withdrawn by erythrocytes (W(I)) from the hypotonic solutions and added (W(E)) to the hypertonic solutions.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°C. W(I) was increased by raising or lowering the pH or raising the temperature of the cell suspension. W(E) x W(I) ≠ 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.