The effect of ammonium, phosphate, potassium, and hypotonicity on stored red cells

The use of an experimental solution that maintained high ATP levels and produced greater than 70 percent viability of stored red cells (RBCs) for up to 18 weeks has been described by other investigators. This solution differed markedly from conventional storage media in that it lacked sodium; contained high concentrations of potassium, ammonium, and phosphate; and was hypotonic. It was not clear which feature or features were responsible for the observed effects. The effects of ammonium, phosphate, potassium, and hypotonicity on stored RBCs have been examined. It was determined that ammonium and phosphate were the important factors in ATP maintenance. The biochemical mechanism by which ammonium acts was studied. In fresh human blood samples, ammonium was found to relieve phosphofructokinase from inhibition by increased ATP concentrations, to have no significant effect on adenine phosphoribosyl transferase activity, and, unexpectedly, to increase the activity of AMP deaminase. Despite prolonged ATP maintenance by ammonium and phosphate-containing storage media, satisfactory viability of RBCs stored up to 77 days was not demonstrated in the rabbit transfusion model.