title: Alkaline CPD and the preservation of RBC 2,3-DPG.
abstract: BACKGROUND
  Concentrations of 2,3-DPG decline rapidly in the first week of RBC storage because of the low pH of conventional storage solutions. Alkaline additive solutions, which can preserve RBCs for up to 11 weeks, still do not preserve 2,3-DPG because the starting pH is below 7.2.
  
  
  METHODS
  Alkaline CPD (pH=8.7) was made with trisodium citrate, dextrose, and disodium phosphate. Twelve units of whole blood were collected into heparin and pooled in groups of four units. Each pool was then aliquoted into four units; 63 mL of CPD with pH 5.7, 6.5, 7.5, or 8.7 was added to one unit of each pool, and 300 mL of the alkaline experimental additive solution-76 was added. In Study 2, 12 units were collected into alkaline CPD, pooled in groups of four, aliquoted as described, and stored in four variants of experimental additive solution-76 containing 0, 9, 18, and 27 mM of disodium phosphate. RBC ATP and 2,3-DPG concentrations, intracellular and extracellular pH and phosphate concentrations, hemolysis, and other measures of RBC metabolism and function were measured weekly.
  
  
  RESULTS
  RBCs stored in more alkaline conditions made 2,3-DPG, but at the expense of ATP. Concentrations of 2,3-DPG decreased after 2 weeks storage, but ATP concentrations never fully recovered. Providing more phosphate both increased the duration of 2,3-DPG persistence and raised ATP concentrations in the later stages of storage.
  
  
  CONCLUSIONS
  Maintaining both 2,3-DPG and ATP requires both high pH and high concentrations of phosphate.
authors.affiliation: Blood Research Detachment, Walter Reed Army Institute of Research, Silver Spring, MD 20307, USA. jhess@umm.edu
authors.forename: John R
authors.initials: JR
authors.lastname: Hess
authors.forename: Heather R
authors.initials: HR
authors.lastname: Hill
authors.forename: Cynthia K
authors.initials: CK
authors.lastname: Oliver
authors.forename: Lloyd E
authors.initials: LE
authors.lastname: Lippert
authors.forename: Tibor J
authors.initials: TJ
authors.lastname: Greenwalt
mesh_terms: D019794:2,3-Diphosphoglycerate / Q000097:blood*; D000255:Adenosine Triphosphate / Q000097:blood; D000328:Adult; D001793:Blood Preservation; D002470:Cell Survival; D002951:Citrates / Q000494:pharmacology*; D004912:Erythrocytes / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D005110:Extracellular Space / Q000737:chemistry; D005947:Glucose / Q000494:pharmacology*; D006461:Hemolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000737:chemistry; D007552:Isotonic Solutions / Q000494:pharmacology*; D009994:Osmolar Concentration; D013997:Time Factors
chemical_list: D002951:Citrates; D007552:Isotonic Solutions; D019794:2,3-Diphosphoglycerate; C007077:citrate phosphate dextrose; D000255:Adenosine Triphosphate; D005947:Glucose