title: Endothelin-1 increases superoxide production in human coronary artery bypass grafts.
abstract: OBJECTIVE
  Endothelin-1 (ET-1) has been shown to increase endothelial superoxide (O(2)(-)) production in experimental animal models. It is unclear whether ET-1 increases O(2)(-) production in humans. We sought to elucidate whether ET-1 increases O(2)(-) production in human vessels and to identify the mechanism behind this effect.
  
  
  METHODS
  Segments of internal mammary artery (IMA) and human saphenous vein (HSV) were harvested from 90 patients undergoing elective coronary artery bypass graft surgery. Paired vessel rings were incubated in the presence and absence of ET-1 (10(-10)M), the ET(A) receptor antagonist BQ123 alone, or in combination with the ET(B) receptor antagonist BQ788 (dual BQ) and known inhibitors of sources of O(2)(-) and further analysed for O(2)(-) production using lucigenin-enhanced chemiluminescence and DHE fluorescence.
  
  
  RESULTS
  ET-1 increased O(2)(-) production in both IMA (2.6 ± 1.5 vs. 1.4 ± 0.8 relative light units/s/mg tissue (RLU); n=33; p < 0.0001) and HSV (1.4 ± 0.8 vs. 1.1 ± 0.6 RLU; n=24; p<0.05). The increase in O(2)(-)production induced by ET-1 in IMA was inhibited by co-incubation with dual BQ (p < 0.05; n=15) and BQ123 (p<0.05; n = 17). Of known O(2)(-) inhibitors, only incubation with Tiron and diphenyleneiodonium resulted in a significant reduction in ET-mediated O(2)(-) production.
  
  
  CONCLUSIONS
  ET-1 increases O(2)(-) production especially in human arteries and less so in veins from patients with coronary artery disease via a receptor-dependent pathway involving a flavin dependent enzyme which is likely to be NADPH oxidase. Production of O(2)(-) may be an important factor underlying the negative effects of ET-1 on vascular function such as impairment of endothelium-dependent vasodilatation and pro-inflammatory effects.
authors.affiliation: Karolinska Institutet, Department of Medicine, Cardiology unit, Karolinska University Hospital, Stockholm, Sweden. ruha.cerrato@karolinska.se
authors.forename: R
authors.initials: R
authors.lastname: Cerrato
authors.forename: C
authors.initials: C
authors.lastname: Cunnington
authors.forename: M J
authors.initials: MJ
authors.lastname: Crabtree
authors.forename: C
authors.initials: C
authors.lastname: Antoniades
authors.forename: J
authors.initials: J
authors.lastname: Pernow
authors.forename: K M
authors.initials: KM
authors.lastname: Channon
authors.forename: F
authors.initials: F
authors.lastname: Böhm
mesh_terms: D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt / Q000494:pharmacology; D000368:Aged; D001026:Coronary Artery Bypass; D003324:Coronary Artery Disease / Q000503:physiopathology*; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1 / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D006801:Humans; D008163:Luminescent Measurements; D008297:Male; D008323:Mammary Arteries / Q000378:metabolism; D008875:Middle Aged; D009842:Oligopeptides / Q000494:pharmacology; D009861:Onium Compounds / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000378:metabolism; D012501:Saphenous Vein / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*
chemical_list: D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1; D009842:Oligopeptides; D009861:Onium Compounds; D010456:Peptides, Cyclic; D010880:Piperidines; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D013481:Superoxides; C086539:BQ 788; D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt; C007517:diphenyleneiodonium; C072247:cyclo(Trp-Asp-Pro-Val-Leu)