title: CO2 -dependent metabolic modulation in red blood cells stored under anaerobic conditions.
abstract: BACKGROUND
  Anaerobic red blood cell (RBC) storage reduces oxidative damage, maintains adenosine triphosphate (ATP) and 2,3-diphosphoglycerate (DPG) levels, and has superior 24-hour recovery at 6 weeks compared to standard storage. This study will determine if removal of CO2 during O2 depletion by gas exchange may affect RBCs during anaerobic storage.
  
  
  METHODS
  This is a matched three-arm study (n = 14): control, O2 and CO2 depleted with Ar (AN), and O2 depleted with 95%Ar/5%CO2 (AN[CO2 ]). RBCs in additives AS-3 or OFAS-3 were evenly divided into three bags, and anaerobic conditions were established by gas exchange. Bags were stored at 1 to 6°C in closed chambers under anaerobic conditions or ambient air, sampled weekly for up to 9 weeks for a panel of in vitro tests. A full metabolomics screening was conducted for the first 4 weeks of storage.
  
  
  RESULTS
  Purging with Ar (AN) results in alkalization of the RBC and increased glucose consumption. The addition of 5% CO2 to the purging gas prevented CO2 loss with an equivalent starting and final pH and lactate to control bags (p > 0.5, Days 0-21). ATP levels are higher in AN[CO2 ] (p < 0.0001). DPG was maintained beyond 2 weeks in the AN arm (p < 0.0001). Surprisingly, DPG was lost at the same rate in both control and AN[CO2 ] arms (p = 0.6).
  
  
  CONCLUSIONS
  Maintenance of ATP in the AN[CO2 ] arm demonstrates that ATP production is not solely a function of the pH effect on glycolysis. CO2 in anaerobic storage prevented the maintenance of DPG, and DPG production appears to be pH dependent. CO2 as well as O2 depletion provides metabolic advantage for stored RBCs.
authors.affiliation: Pathology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire.
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Dumont
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Colorado Denver-Anschutz Medical Campus, Aurora, Colorado.|Metabolomics Core, Mass Spectrometry Shared Resource-SOM, University of Colorado Denver, Aurora, Colorado.
authors.forename: Angelo
authors.initials: A
authors.lastname: D'Alessandro
authors.affiliation: Pathology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire.|Pathology, Dartmouth-Hitchcock, Lebanon, New Hampshire.
authors.forename: Zbigniew M
authors.initials: ZM
authors.lastname: Szczepiorkowski
authors.affiliation: New Health Sciences, Bethesda, Maryland.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Yoshida
mesh_terms: D019794:2,3-Diphosphoglycerate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000693:Anaerobiosis; D001793:Blood Preservation; D002245:Carbon Dioxide / Q000378:metabolism* / Q000494:pharmacology; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D006019:Glycolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000378:metabolism
chemical_list: D019794:2,3-Diphosphoglycerate; D002245:Carbon Dioxide; D000255:Adenosine Triphosphate; D010100:Oxygen