title: Adenosine prevents neutrophil adhesion to human endothelial cells after hypoxia/reoxygenation.
abstract: BACKGROUND
  Neutrophil adhesion to vascular endothelium has been implicated in the pathogenesis of myocardial injury after ischaemia/reperfusion (IR) and the "no-reflow" phenomenon. Adenosine and sodium-nitroprusside (SNP) have been used clinically to ameliorate this injury. We set out to establish a human cellular model for the study of IR and to evaluate the effects of adenosine and SNP on neutrophil adhesion in vitro.
  
  
  METHODS
  Cultured human umbilical vein endothelial cells (HUVEC) were exposed to hypoxia (5% CO2, 95% N2) or normoxia (room air, 5% CO2) for 2 h, followed by reoxygenation for 30 min (IR condition). Human neutrophils were then added together with adenosine (50 microM), SNP (10 microM) or no additive (control). After incubation for 1 h, neutrophil adhesion to endothelial cells was quantified via automated cell counts. The experiment was repeated with the adenosine treatment alone, with and without the addition of the adenosine A2A receptor blocker ZM-241385.
  
  
  RESULTS
  Compared with baseline neutrophil adhesion after normoxia, hypoxia followed by reoxygenation increased adhesion to 189+/-43% (p=0.01), but this effect was prevented by the addition of adenosine (109+/-17%, p=NS compared to control conditions). SNP did not affect the increased adhesion caused by hypoxia (166+/-25%, p=NS). The addition of ZM-241385 did not inhibit the effect of adenosine on neutrophil adhesion after hypoxia/reoxygenation.
  
  
  CONCLUSIONS
  Exposure of human endothelial cells to hypoxia/reoxygenation causes increased neutrophil adhesion. This effect is prevented by adenosine, but not mediated by the A2A receptor. SNP does not prevent neutrophil adhesion after IR in vitro.
authors.affiliation: The Heart Research Institute, 145 Missenden Road, Camperdown, N.S.W. Australia, 2050, The University of Sydney, Department of Medicine, Sydney, Australia.
authors.forename: J G
authors.initials: JG
authors.lastname: Kilian
authors.forename: S
authors.initials: S
authors.lastname: Nakhla
authors.forename: D P
authors.initials: DP
authors.lastname: Sieveking
authors.forename: D S
authors.initials: DS
authors.lastname: Celermajer
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D015687:Cell Hypoxia; D002478:Cells, Cultured; D042783:Endothelial Cells; D006801:Humans; D009504:Neutrophils / Q000187:drug effects* / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology*; D010100:Oxygen / Q000008:administration & dosage; D015427:Reperfusion Injury / Q000209:etiology; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D009599:Nitroprusside; D000241:Adenosine; D010100:Oxygen