title: The effect of reactive oxygen species on whole blood aggregation and the endothelial cell-platelet interaction in patients with coronary heart disease.
abstract: BACKGROUND
  The effect of reactive oxygen species (ROS) on platelet function in coronary heart disease (CHD) is complex and poorly defined. Platelet aggregation studies in healthy volunteers have demonstrated contrasting results when platelets are exposed to ROS. We investigated the effect of ROS on whole blood aggregation (WBA) and the endothelial cell-platelet interaction in patients with CHD.
  
  
  RESULTS
  ROS generated by xanthine and xanthine oxidase caused a concentration-dependent inhibition of WBA in blood from healthy donors and patients with CHD. In patients with CHD, 100 μM xanthine and 100 mU/ml xanthine oxidase inhibited WBA in response to 3 μg/ml collagen by 28.9% (95% CI 15.9%-41.8%, p<0.001) and in response to 5 μM ADP by 36.0% (95% CI 9.6%-62.4%, p=0.005). Using nitrotyrosine expression, platelets isolated from patients with CHD were found to be susceptible to peroxynitrite damage. The addition of 1 × 10(5) cultured endothelial cells inhibited WBA in response to 3 μg/ml collagen by 31.2% (95% CI 12.2%-50.2%, p<0.05) and in response to 5 μM ADP by 31.6% (95% CI 2.5-60.7%, p<0.05). Addition of xanthine and xanthine oxidase did not alter this effect, however pre-treatment of endothelial cells with a nitric oxide synthase inhibitor (L-NAME) partly reversed the inhibition.
  
  
  CONCLUSIONS
  ROS inhibit WBA in blood from patients with CHD. Whilst endothelial cells also inhibit WBA, the effect is attenuated by L-NAME, suggesting that nitric oxide is likely to remain an important protective mechanism against thrombosis in CHD.
authors.affiliation: Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0NR, UK. jonnywatt@hotmail.com
authors.forename: Jonathan
authors.initials: J
authors.lastname: Watt
authors.forename: Marie-Ann
authors.initials: MA
authors.lastname: Ewart
authors.forename: Fiona H
authors.initials: FH
authors.lastname: Greig
authors.forename: Keith G
authors.initials: KG
authors.lastname: Oldroyd
authors.forename: Roger M
authors.initials: RM
authors.lastname: Wadsworth
authors.forename: Simon
authors.initials: S
authors.lastname: Kennedy
mesh_terms: D000368:Aged; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism; D002450:Cell Communication / Q000187:drug effects; D003327:Coronary Disease / Q000097:blood / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006487:Hemostasis / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D019820:Xanthine / Q000378:metabolism; D014969:Xanthine Oxidase / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; D019820:Xanthine; C002744:3-nitrotyrosine; D014443:Tyrosine; D014969:Xanthine Oxidase; D019331:NG-Nitroarginine Methyl Ester