title: Small doses of mercury increase arterial pressure reactivity to phenylephrine in rats.
abstract: Mercury reduces cardiac contractility and arterial pressure at micromolar concentrations. We investigated the actions of 680ng/kg HgCl(2) on arterial pressure, heart rate (HR) and on the pressor reactivity to phenylephrine (PHE) in rats before and 1h after HgCl(2) administration and after hexametonium, verapamil and tempol treatments. HgCl(2) increased baseline systolic (SAP) and diastolic pressure (DAP) and HR, sensitivity (pD(2)) and maximal response (E(max)) to PHE pressor reactivity. Hexametonium and verapamil reduced baseline pressures and HR that increased after HgCl(2) treatment. Hexametonium did not change pD(2) or E(max) to PHE but verapamil reduced them. These parameters increased after HgCl(2) administration. Tempol did not alter baseline pressures, HR or PHE reactivity before and after HgCl(2). Results suggest that HgCl(2) increases SAP, DAP, HR and PHE reactivity; autonomic reflexes reduces HgCl(2) action; baseline pressure level do not interfere on HgCl(2) pressor effects but free radicals seems to be involved.
authors.affiliation: Department of Physiological Sciences, Federal University of Espirito Santo, Vitoria, ES, Brazil.
authors.forename: Adriana Caiado
authors.initials: AC
authors.lastname: Machado
authors.forename: Alessandra Simão
authors.initials: AS
authors.lastname: Padilha
authors.forename: Giulia Alessandra
authors.initials: GA
authors.lastname: Wiggers
authors.forename: Fabiana Dayse Magalhães
authors.initials: FD
authors.lastname: Siman
authors.forename: Ivanita
authors.initials: I
authors.lastname: Stefanon
authors.forename: Dalton Valentim
authors.initials: DV
authors.lastname: Vassallo