EUROPACE ADVANCE ACCESS ORIGINALLY PUBLISHED ONLINE ON MAY 30, 2008 Europace 2008 10(7):868-876; doi:10.This Article All Versions of this Article: 10/7/868 _most recent_ Services Google Scholar PubMed Social Bookmarking Repolarization ANTIBODIES WITH BETA-ADRENERGIC ACTIVITY FROM CHRONIC CHAGASIC PATIENTS MODULATE THE QT INTERVAL AND M CELL ACTION POTENTIAL DURATION EMILIANO HORACIO MEDEI1,, JOS H.ROBERTO C.LUCIANE BARCELLOS1, MASAKO O.SERGE SICOURI4, MARCELO V.ANTONIO C.DE CARVALHO1 _ 1 Instituto de Biofsica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Bloco GCCS, Cidade Universitria, Ilha do Fundo, Rio de Janeiro, RJ 21949-900, Brasil; 2 Hospital Universitrio Clementino Fraga Filho, Universidade do Brasil, Rio de Janeiro, Brasil; 3 Fundao CECIERJ, Rio de Janeiro, Brasil; 4 Masonic Medical Research Laboratory, Utica, NY, USA; 5 Hospital Ramos Mejia, Cardiac Division, Buenos Aires, Argentina _ Aims: The aim of this study was to investigate whether the sera from chronic chagasic patients (CChPs) with beta-1 adrenergic activity (Ab-) can modulate ventricular repolarization.Activity has been described in CChP.The L-type calcium current and heart rate in isolated hearts, but its effects on ventricular repolarization has not been described.Methods and results: In isolated rabbit hearts, under pacing condition, QT interval was measured under Ab- perfusion.Was also tested in guinea pig ventricular M cells.The immunoglobulin fraction (IgG-) of the Ab- was tested on Ito, ICa, and Iks currents in rat, rabbit, and guinea pig myocytes, respectively.Activity shortened the QT interval.Effect was abolished in the presence of propranolol.Sera from CChP without beta-adrenergic activity (Ab-) did not modulate QT interval.M cell action potential duration (APD) was reversibly shortened by Ab-.Inhibited this effect of Ab-, and Ab- did not modulate the AP of M cells.Was not modulated by isoproterenol nor by IgG-.IgG- increased ICa and IKs.The shortening of the QT interval and APD in M cells and the increase of IKs and ICa induced by IgG- contribute to repolarization changes that may trigger malignant ventricular arrhythmias observed in patients with chronic chagasic or idiopathic cardiomyopathy.KEY WORDS: Antibodies, Chagas' disease, Electrophysiology, M cells, QT interval Corresponding author.+55 21 25626558; fax: +55 21 22808193.Br/emedei70{at}hotmail Manuscript submitted 4 March 2008.After revision 6 May 2008.Read more A case of benign metastasizing leiomyoma treated by surgical castration followed by an aromatase inhibitor, anastrozole
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