Authors: Araujo, Alex Sander Da Rosa; Miranda, Madalena Freitas Silva de; Oliveira, Ubirajara de; Fernandes, Tânia; Llesuy, Susana Francisca; Kucharski, Luiz Carlos Rios; Khaper, Neelam; Belló Klein, Adriane
Publication Date: 2010.
The purpose of this study was to determine whether decreased oxidative stress would increase the resistance to cardiac contracture induced by H 2O2 in hypothyroid rats. Male Wistar rats were divided into two groups: control and hypothyroid. Hypothyroidism was induced via thyroidectomy. Four weeks post surgery, blood samples were collected to perform thyroid hormone assessments, and excised hearts were perfused at a constant flow with or without H2O2 (1 mmol/L), being divided into two sub-groups: control, hypothyroid, control + H2O2, hypothyroid + H2O2. Lipid peroxidation (LPO) was evaluated by chemiluminescence (CL) and thiobarbituric acid reactive substances (TBARS) methods, and protein oxidation by carbonyls assay in heart homogenates. Cardiac tissue was also screened for superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities, and for total radical-trapping antioxidant potential (TRAP). Analyses of SOD and glutathione-S-transferase (GST) protein expression were also performed in heart homogenates. Hypothyroid hearts were found to be more resistant to H2O2-induced contracture (60% elevation in LVEDP) as compared to control. CL, TBARS, carbonyl, as well as SOD, CAT, GPx activities and TRAP levels were reduced (35, 30, 40, 30, 16, 25, and 33%, respectively) in the cardiac homogenates of the hypothyroid group as compared to controls. A decrease in SOD and GST protein levels by 20 and 16%, respectively, was also observed in the hypothyroid group. These results suggest that a hypometabolic state caused by thyroid hormone deficiency can lead to an improved response to H2O2 challenge and is associated with decreased oxidative myocardial damage.
Author affiliation: Araujo, Alex Sander Da Rosa. Universidade Federal do Rio Grande do Sul; Brasil
Author affiliation: Miranda, Madalena Freitas Silva de. Universidade Federal do Rio Grande do Sul; Brasil
Author affiliation: Oliveira, Ubirajara de. Universidade Federal do Rio Grande do Sul; Brasil
Author affiliation: Fernandes, Tânia. Universidade Federal do Rio Grande do Sul; Brasil
Author affiliation: Llesuy, Susana Francisca. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; Argentina
Author affiliation: Kucharski, Luiz Carlos Rios. Universidade Federal do Rio Grande do Sul; Brasil
Author affiliation: Khaper, Neelam. Lakehead University; Canadá
Author affiliation: Belló Klein, Adriane. Universidade Federal do Rio Grande do Sul; Brasil
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas