title: The uremic toxin acrolein promotes suicidal erythrocyte death.
abstract: BACKGROUND
  Anemia is a major complication of end stage renal disease. The anemia is mainly the result of impaired formation of erythrocytes due to lack of erythropoietin and iron deficiency. Compelling evidence, however, points to the contribution of accelerated erythrocyte death, which decreases the life span of circulating erythrocytes. Erythrocytes may enter suicidal death or eryptosis, which is characterized by cell shrinkage and by cell membrane scrambling with phosphatidylserine-exposure at the erythrocyte surface. Triggers of eryptosis include increase of cytosolic Ca(2+)-activity ([Ca(2+)]i). Erythrocytes could be sensitized to cytosolic Ca(2+) by ceramide. In end stage renal disease, eryptosis may possibly be stimulated by uremic toxins. The present study explored, whether the uremic toxin acrolein could trigger eryptosis.
  
  
  METHODS
  Cell volume was estimated from forward scatter, phosphatidylserine-exposure from annexin-V-binding, hemolysis from hemoglobin release, [Ca(2+)]i from Fluo3-fluorescence, and ceramide from fluorescent antibodies.
  
  
  RESULTS
  A 48 h exposure to acrolein (30 － 50 µM) did not significantly modify [Ca(2+)]i but significantly decreased forward scatter and increased annexin-V-binding. Acrolein further triggered slight, but significant hemolysis and increased ceramide formation in erythrocytes. Acrolein (50 µM) induced annexin-V-binding was significantly blunted in the nominal absence of extracellular Ca(2+). Acrolein augmented the annexin-V-binding following treatment with Ca(2+) ionophore ionomycin (1 µM).
  
  
  CONCLUSIONS
  Acrolein stimulates suicidal erythrocyte death or eryptosis, an effect at least in part due to stimulation of ceramide formation with subsequent sensitisation of the erythrocytes to cytosolic Ca(2+).
authors.affiliation: Department of Physiology, University of Tuebingen, Gmelinstraße 5, 72076 Tuebingen, Germany.
authors.forename: Mohamed Siyabeldin E
authors.initials: MS
authors.lastname: Ahmed
authors.forename: Henning
authors.initials: H
authors.lastname: Langer
authors.forename: Majed
authors.initials: M
authors.lastname: Abed
authors.forename: Jakob
authors.initials: J
authors.lastname: Voelkl
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000171:Acrolein / Q000633:toxicity*; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects*; D048429:Cell Size; D002518:Ceramides / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects*; D005434:Flow Cytometry; D006461:Hemolysis; D006801:Humans; D066298:In Vitro Techniques; D010718:Phosphatidylserines / Q000378:metabolism; D014511:Uremia / Q000378:metabolism*
chemical_list: D017304:Annexin A5; D002518:Ceramides; D010718:Phosphatidylserines; D000171:Acrolein; D002118:Calcium