title: Endothelial dysfunction of rat coronary arteries after exposure to low concentrations of mercury is dependent on reactive oxygen species.
abstract: OBJECTIVE
  Exposure to mercury is known to increase cardiovascular risk but the underlying mechanisms are not well explored. We analysed whether chronic exposure to low mercury doses affects endothelial modulation of the coronary circulation.
  
  
  METHODS
  Left coronary arteries and hearts from Wistar rats treated with either HgCl(2) (first dose 4.6 µg·kg(-1) , subsequent doses 0.07 µg·kg(-1) day(-1) , 30 days) or vehicle were used. Endothelial cells from pig coronary arteries incubated with HgCl(2) were also used.
  
  
  RESULTS
  Mercury treatment increased 5-HT-induced vasoconstriction but reduced acetylcholine-induced vasodilatation. It also reduced nitric oxide (NO) production and the effects of NO synthase inhibition with L-NAME (100 µmol·L(-1) ) on 5-HT and acetylcholine responses. Superoxide anion production and mRNA levels of NOX-1 and NOX-4 were all increased. The superoxide anion scavenger tiron (1 mmol·L(-1)) reduced 5-HT responses and increased acetylcholine responses only in vessels from mercury-treated rats. In isolated hearts from mercury-treated rats, coronary perfusion and diastolic pressure were unchanged, but developed isovolumetric systolic pressure was reduced. In these hearts, L-NAME increased coronary perfusion pressure and diastolic pressure while it further reduced developed systolic pressure.
  
  
  CONCLUSIONS
  Chronic exposure to low doses of mercury promotes endothelial dysfunction of coronary arteries, as shown by decreased NO bioavailability induced by increased oxidative stress. These effects on coronary function increase resistance to flow, which under overload conditions might cause ventricular contraction and relaxation impairment. These findings provide further evidence that mercury, even at low doses, could be an environmental risk factor for cardiovascular disease.
authors.affiliation: Department of Pharmacology, School of Medicine, Universidad Autónoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid, Spain.
authors.forename: Lorena B
authors.initials: LB
authors.lastname: Furieri
authors.forename: María
authors.initials: M
authors.lastname: Galán
authors.forename: María S
authors.initials: MS
authors.lastname: Avendaño
authors.forename: Ana B
authors.initials: AB
authors.lastname: García-Redondo
authors.forename: Andrea
authors.initials: A
authors.lastname: Aguado
authors.forename: Sonia
authors.initials: S
authors.lastname: Martínez
authors.forename: Victoria
authors.initials: V
authors.lastname: Cachofeiro
authors.forename: M Visitación
authors.initials: MV
authors.lastname: Bartolomé
authors.forename: María J
authors.initials: MJ
authors.lastname: Alonso
authors.forename: Dalton V
authors.initials: DV
authors.lastname: Vassallo
authors.forename: Mercedes
authors.initials: M
authors.lastname: Salaices
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects* / Q000473:pathology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000473:pathology; D008297:Male; D008627:Mercuric Chloride / Q000008:administration & dosage / Q000633:toxicity*; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013552:Swine; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
chemical_list: D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D008627:Mercuric Chloride