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Parasitology ; 136(8): 905-18, 2009 Jul.
Article in English | MEDLINE | ID: mdl-19523250

ABSTRACT

Changes in the cardiac beta-adrenergic system in early stages of Trypanosoma cruzi infection have been described. Here, we studied an early (135 days post-infection-p.i.) and a late stage (365 days p.i.) of the cardiac chronic form of the experimental infection (Tulahuen or SGO-Z12 strains), determining plasma epinephrine and norepinephrine levels, beta-receptor density, affinity and function, cardiac cAMP concentration and phosphodiesterase activity, cardiac contractility, and the presence of beta-receptor autoantibodies. Tulahuen-infected mice presented lower epinephrine and norepinephrine levels; lower beta-receptor affinity and density; a diminished norepinephrine response and higher cAMP levels in the early stage, and a basal contractility similar to non-infected controls in the early and augmented in the late stage. The Tulahuen strain induced autoantibodies with weak beta-receptor interaction. SGO-Z12-infected mice presented lower norepinephrine levels and epinephrine levels that diminished with the evolution of the infection; lower beta-receptor affinity and an increased density; unchanged epinephrine and norepinephrine response in the early and a diminished response in the late stage; higher cAMP levels and unchanged basal contractility. The SGO-Z12 isolate induced beta-receptor autoantibodies with strong interaction with the beta-receptors. None of the antibodies, however, acted a as beta-receptor agonist. The present results demonstrate that this system is seriously compromised in the cardiac chronic stage of T. cruzi infection.


Subject(s)
Chagas Cardiomyopathy/physiopathology , Receptors, Adrenergic, beta/metabolism , Trypanosoma cruzi , Adrenergic beta-Agonists/blood , Adrenergic beta-Agonists/pharmacology , Animals , Antibody Specificity , Autoantibodies/blood , Autoantibodies/immunology , Chagas Cardiomyopathy/blood , Chagas Cardiomyopathy/pathology , Chronic Disease , Cyclic AMP/metabolism , Epinephrine/blood , Epinephrine/pharmacology , Heart/drug effects , Heart/physiopathology , Mice , Myocardial Contraction/drug effects , Myocardium/metabolism , Myocardium/pathology , Norepinephrine/blood , Norepinephrine/pharmacology , Phosphoric Diester Hydrolases/metabolism , Receptors, Adrenergic, beta/analysis
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