title: The signaling pathway for aldosterone-induced mitochondrial production of superoxide anion in the myocardium.
abstract: Mineralocorticoid receptor (MR) antagonists decrease morbidity and mortality in heart failure patients for whom oxidative stress is usual; however, the underlying mechanism for this protection is unclear. Since aldosterone stimulates reactive oxygen species (ROS) production in several tissues, we explored its effect and the intracellular pathway involved in the rat myocardium. Aldosterone dose-dependently increased O2(-) production in myocardial slices. At 10 nmol/L, aldosterone increased O2(-) to 165 ± 8.8% of control, an effect prevented not only by the MR antagonists eplerenone and spironolactone (107 ± 7.8 and 103 ± 5.3%, respectively) but also by AG1478 (105 ± 8.0%), antagonist of the EGF receptor (EGFR). Similar results were obtained by silencing MR expression through the direct intramyocardial injection of a lentivirus coding for a siRNA against the MR. The aldosterone effect on O2(-) production was mimicked by the mKATP channel opener diazoxide and blocked by preventing its opening with 5-HD and glibenclamide, implicating the mitochondria as the source of O2(-). Inhibiting the respiratory chain with rotenone or mitochondrial permeability transition (MPT) with cyclosporine A or bongkrekic acid also canceled aldosterone-induced O2(-) production. In addition, aldosterone effect depended on NADPH oxidase and phosphoinositide 3-kinase activation, as apocynin and wortmannin, respectively, inhibited it. EGF (0.1 μg/mL) similarly increased O2(-), although in this case MR antagonists had no effect, suggesting that EGFR transactivation occurred downstream from MR activation. Inhibition of mKATP channels, the respiratory chain, or MPT did not prevent Akt phosphorylation, supporting that it happened upstream of the mitochondria. Importantly, cardiomyocytes were confirmed as a source of aldosterone induced mitochondrial ROS production in experiments performed in isolated cardiac myocytes. These results allow us to speculate that the beneficial effects of MR antagonists in heart failure may be related to a decrease in oxidative stress.
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, UNLP-CONICET, Argentina.
authors.forename: M B
authors.initials: MB
authors.lastname: Nolly
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, UNLP-CONICET, Argentina.
authors.forename: C I
authors.initials: CI
authors.lastname: Caldiz
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, UNLP-CONICET, Argentina.
authors.forename: A M
authors.initials: AM
authors.lastname: Yeves
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, UNLP-CONICET, Argentina.
authors.forename: M C
authors.initials: MC
authors.lastname: Villa-Abrille
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, UNLP-CONICET, Argentina.
authors.forename: P E
authors.initials: PE
authors.lastname: Morgan
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, UNLP-CONICET, Argentina.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Amado Mondaca
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, UNLP-CONICET, Argentina.
authors.forename: Enrique L
authors.initials: EL
authors.lastname: Portiansky
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, UNLP-CONICET, Argentina.
authors.forename: G E
authors.initials: GE
authors.lastname: Chiappe de Cingolani
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, UNLP-CONICET, Argentina.
authors.forename: H E
authors.initials: HE
authors.lastname: Cingolani
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, UNLP-CONICET, Argentina. Electronic address: iennis@med.unlp.edu.ar.
authors.forename: I L
authors.initials: IL
authors.lastname: Ennis
mesh_terms: D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism*; D008954:Models, Biological; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism*
chemical_list: D013481:Superoxides; D000450:Aldosterone
keywords: 5-HD; 5-hydroxydecanoate; CsA; DHE; EGFR; HF; MPT; MR; Mineralocorticoid receptor; Oxidative stress; ROS; Transactivation; cyclosporine A; dihydroethidium; epidermal growth factor receptor; heart failure; mK(ATP); mineralocorticoid receptor; mitochondrial ATP-dependent potassium; permeability transition pore; reactive oxygen species; siRNA