title: Propensity of red blood cells to undergo P2X7 receptor-mediated phosphatidylserine exposure does not alter during in vivo or ex vivo aging.
abstract: BACKGROUND
  Phosphatidylserine (PS) exposure facilitates the removal of red blood cells (RBCs) from the circulation, potentially contributing to the loss of stored RBCs after transfusion, as well as senescent RBCs. Activation of the P2X7 receptor by extracellular adenosine 5'-triphosphate (ATP) can induce PS exposure on freshly isolated human RBCs, but whether this process occurs in stored RBCs or changes during RBC aging is unknown.
  
  
  METHODS
  RBCs were processed and stored according to Australian blood banking guidelines. PS exposure was determined by annexin V binding and flow cytometry. Efficacy of P2X antagonists was assessed by flow cytometric measurements of ATP-induced ethidium+ uptake in RPMI 8226 cells. Osmotic fragility was assessed by lysis in hypotonic saline. RBCs were fractionated by discontinuous density centrifugation.
  
  
  RESULTS
  ATP (1 mmol/L) induced PS exposure on RBCs stored for less than 1 week. This process was near-completely inhibited by the P2X7 antagonists A438079 and AZ10606120 and the P2X1/P2X7 antagonist MRS2159 but not the P2X1 antagonist NF499. ATP-induced PS exposure on RBCs was not dependent on K+, Na+, or Cl- fluxes. ATP did not alter the osmotic fragility of stored RBCs. ATP-induced PS exposure was similar between RBCs of different densities. ATP-induced PS exposure was also similar between RBCs stored for less than 1 week or for 6 weeks.
  
  
  CONCLUSIONS
  The propensity of RBCs to undergo P2X7-mediated PS exposure does not alter during in vivo and ex vivo aging. Thus, P2X7 activation is unlikely to be involved in the removal of senescent RBCs or stored RBCs after transfusion.
authors.affiliation: School of Biological Sciences.|Centre for Medical and Molecular Bioscience, University of Wollongong.|Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.
authors.forename: Reece A
authors.initials: RA
authors.lastname: Sophocleous
authors.affiliation: School of Biological Sciences.|Centre for Medical and Molecular Bioscience, University of Wollongong.|Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.
authors.forename: Phillip R F
authors.initials: PR
authors.lastname: Mullany
authors.affiliation: Research and Development, Australian Red Cross Blood Service, Sydney, NSW, Australia.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Winter
authors.affiliation: Research and Development, Australian Red Cross Blood Service, Sydney, NSW, Australia.
authors.forename: Denese C
authors.initials: DC
authors.lastname: Marks
authors.affiliation: School of Biological Sciences.|Centre for Medical and Molecular Bioscience, University of Wollongong.|Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.
authors.forename: Ronald
authors.initials: R
authors.lastname: Sluyter
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000097:blood / Q000494:pharmacology; D000634:Aminoquinolines / Q000494:pharmacology; D017304:Annexin A5 / Q000378:metabolism; D001391:Azo Compounds / Q000494:pharmacology; D001557:Benzenesulfonates / Q000494:pharmacology; D001793:Blood Preservation; D016922:Cellular Senescence; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008563:Membrane Lipids / Q000097:blood*; D009996:Osmotic Fragility; D010718:Phosphatidylserines / Q000097:blood*; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D058474:Receptors, Purinergic P2X1 / Q000502:physiology; D058486:Receptors, Purinergic P2X7 / Q000502:physiology*; D013777:Tetrazoles / Q000494:pharmacology
chemical_list: C523668:3-(5-(2,3-dichlorophenyl)-1H-tetrazol-1-yl)methylpyridine; C110258:4,4,',4'',4'''-(carbonylbis(imino-5,1,3-benzenetriylbis(carbonylimino)))tetrakis(benzene-1,3-disulfonate); C000602458:AZ10606120; D000634:Aminoquinolines; D017304:Annexin A5; D001391:Azo Compounds; D001557:Benzenesulfonates; C000602459:MRS2159; D008563:Membrane Lipids; D010718:Phosphatidylserines; D058920:Purinergic P2X Receptor Antagonists; D011725:Pyridines; D058474:Receptors, Purinergic P2X1; D058486:Receptors, Purinergic P2X7; D013777:Tetrazoles; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; D000218:Adamantane