The respiratory efficiency and flexibility of erythrocytes stored in acid-citrate-dextrose solution.

1. Measurements have been made of the flexibility and respiratory efficiency of erythrocytes stored in acid-citrate-dextrose (ACD).2. The rate of packing of stored blood, during centrifugation, indicates that the red blood cells are relatively inflexible.3. Spectrophotometric observations, using the rapid-mixing and stopped-flow technique, indicate that the rate of egress of oxygen from HbO(2) in these erythrocytes is significantly reduced. This is not due to a change of the chemical rate of dissociation of HbO(2).4. Neither factor is significantly reversed by resuspending the cells in Ringer-Locke solution or adjusting to pH 7.4.5. A small improvement is obtained by adding hypertonic NaCl or incubating the blood at 37 degrees C for 1 hr.6. Incubation with adenosine, 25 mu-mole/ml. blood, at 37 degrees C for at least 1 hr, restored both the respiratory function and flexibility to normal.