Studies in red blood cell preservation. 5. Determining the limiting concentrations of NH4Cl and Na2HPO4 needed to maintain red blood cell ATP during storage.

The purpose of the present study was to define the lowest concentrations of ammonium (NH4+) and phosphate (Pi) in an experimental additive solution (EAS) that would support suitable red blood cell (RBC) ATP levels and other in vitro characteristics for at least 84 days. It was determined that ATP maintenance was dependent upon both NH4+ and Pi concentrations. RBCs stored for 84 days in additive solutions containing 10 mM NH4+ and 0, 15, 25 and 40 mM Pi had ATP values averaging 1.87, 2.49, 2.70 and 2.65 mumol/g Hb, respectively. The shedding of exocytic hemoglobin-containing vesicles and percent hemolysis were significantly (p less than 0.001) elevated in the preservative containing 40 mM Pi. These data suggest that an EAS containing 10 mM NH4+ and 15 mM Pi would be optimal for storing RBCs up to 84 days. The extended storage would be particularly advantageous for autologous transfusion programs.