Swelling of Human Red Blood Cells, Preserved with Progesterone, as Determined by Spectrophotometric Measurements

Summary The swelling rate of human red blood cells has been studied by spectrophotometric measurements of the absorbance of erythrocytes dispersed in water or sucrose solutions buffered with sodium phosphate buffer, pH 7.4. The rate of swelling of red cells, prepared from blood stored at 2° in acid-citrate-dextrose solution, increases with increased time of storage. The addition of physiological amounts of progesterone to red blood cells stored in the cold under sterile conditions greatly depresses the increase of the swelling rate; red blood cells preserved for 40 days with addition of progesterone manifest the same rate of swelling as that of red blood cells stored for 10 days without progesterone.