Chronic HgCl2 treatment increases vasoconstriction induced by electrical field stimulation. Role of adrenergic and nitrergic innervation

Javier Blanco-Rivero , Lorena B Furieri , Dalton V Vassallo , Mercedes Salaíces , Gloria Balfagón (1)

1 Fisiología

Objectives: We investigated the possible changes in rat mesenteric artery vascular innervation function caused by chronic exposure to low doses of mercuric chloride (HgCl2), as well as the mechanisms involved. Methods: Rats were divided into two groups: control and HgCl2-treated rats (30 days, 1st dose 4.6 µg/kg, subsequent dose 0.07 µg/kg*day im). Vasomotor response to electrical field stimulation (EFS), noradrenaline (NA) and nitric oxide (NO) donor DEA-NO were studied, neuronal NO synthase (nNOS) and phosphorylated nNOS (P-nNOS) protein expression were analysed and NO, superoxide anions (O2.-) and NA releases were also determined. Results: EFS-induced contraction was higher in the HgCl2-treated group. 1 mmol/L phentolamine decreased the response to EFS to a greater extent in HgCl2-treated rats. HgCl2 treatment increased vasoconstrictor response to exogenous NA and NA release. 0.1 mmol/L L-NAME increased the response to EFS in both experimental groups but the increase was greater in segments from control animals. HgCl2 treatment decreased NO release and increased O2.- production. Vasodilator response to DEA-NO was lower in HgCl2 animals. Tempol increased DEA-NO-induced relaxation to a greater extent in HgCl2-treated animals. nNOS expression was similar in arteries from both experimental groups, while P-nNOS was decreased in segments from HgCl2-treated animals. Conclusion: HgCl2 treatment increased vasoconstrictor response to EFS as a result, at the least, of reduced NO bioavailability and increased adrenergic function. These findings offer further evidence that mercury, even at low concentrations, is an environmental risk factor for cardiovascular disease.

Mots clés: Medicine

Domaines: Médecine humaine et pathologie

Javier Blanco-Rivero, Lorena B Furieri, Dalton V Vassallo, Mercedes Salaíces, Gloria Balfagón. Chronic HgCl2 treatment increases vasoconstriction induced by electrical field stimulation. Role of adrenergic and nitrergic innervation. Clinical Science, 2011, 121 (8), pp.331-341. ⟨10.1042/CS20110072⟩. ⟨hal-00711367⟩