AIMS: The aim of this study was to investigate whether the sera from chronic chagasic patients (CChPs) with beta-1 adrenergic activity (Ab-beta) can modulate ventricular repolarization. Beta-adrenergic activity has been described in CChP. It increases 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-beta perfusion. Beta-adrenergic activity was also tested in guinea pig ventricular M cells. Furthermore, the immunoglobulin fraction (IgG-beta) of the Ab-beta was tested on Ito, ICa, and Iks currents in rat, rabbit, and guinea pig myocytes, respectively. Beta-adrenergic activity shortened the QT interval. This effect was abolished in the presence of propranolol. In addition, sera from CChP without beta-adrenergic activity (Ab-beta) did not modulate QT interval. The M cell action potential duration (APD) was reversibly shortened by Ab-beta. Atenolol inhibited this effect of Ab-beta, and Ab- did not modulate the AP of M cells. Ito was not modulated by isoproterenol nor by IgG-beta. However, IgG-beta increased ICa and IKs. CONCLUSION: The shortening of the QT interval and APD in M cells and the increase of IKs and ICa induced by IgG-beta contribute to repolarization changes that may trigger malignant ventricular arrhythmias observed in patients with chronic chagasic or idiopathic cardiomyopathy.
AIMS: The aim of this study was to investigate whether the sera from chronic chagasic patients (CChPs) with beta-1 adrenergic activity (Ab-beta) can modulate ventricular repolarization. Beta-adrenergic activity has been described in CChP. It increases 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-beta perfusion. Beta-adrenergic activity was also tested in guinea pig ventricular M cells. Furthermore, the immunoglobulin fraction (IgG-beta) of the Ab-beta was tested on Ito, ICa, and Iks currents in rat, rabbit, and guinea pig myocytes, respectively. Beta-adrenergic activity shortened the QT interval. This effect was abolished in the presence of propranolol. In addition, sera from CChP without beta-adrenergic activity (Ab-beta) did not modulate QT interval. The M cell action potential duration (APD) was reversibly shortened by Ab-beta. Atenolol inhibited this effect of Ab-beta, and Ab- did not modulate the AP of M cells. Ito was not modulated by isoproterenol nor by IgG-beta. However, IgG-beta increased ICa and IKs. CONCLUSION: The shortening of the QT interval and APD in M cells and the increase of IKs and ICa induced by IgG-beta contribute to repolarization changes that may trigger malignant ventricular arrhythmias observed in patients with chronic chagasic or idiopathic cardiomyopathy.
Authors: P C Costa; F S Fortes; A B Machado; N A Almeida; E L Olivares; P R Cabral; R C Pedrosa; R C Goldenberg; A C Campos-De-Carvalho; M O Masuda Journal: Braz J Med Biol Res Date: 2000-04 Impact factor: 2.590
Authors: S B Felix; A Staudt; W V Dörffel; V Stangl; K Merkel; M Pohl; W D Döcke; S Morgera; H H Neumayer; K D Wernecke; G Wallukat; K Stangl; G Baumann Journal: J Am Coll Cardiol Date: 2000-05 Impact factor: 24.094
Authors: Leticia L Niborski; Mariana Potenza; Renato G S Chirivi; Leandro Simonetti; Micaela S Ossowski; Vanina Grippo; Maria May; Daniela I Staquicini; Adriana Parodi-Talice; Carlos Robello; Marcelo A Comini; Guillermo D Alonso; Jos M H Raats; Karina A Gómez Journal: EBioMedicine Date: 2021-01-08 Impact factor: 8.143
Authors: H Rodríguez-Angulo; J Toro-Mendoza; J Marques; R Bonfante-Cabarcas; A Mijares Journal: Braz J Med Biol Res Date: 2013-01-11 Impact factor: 2.590