Viral Hepatitis
Copyright ©The Author(s) 2004. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Apr 15, 2004; 10(8): 1171-1175
Published online Apr 15, 2004. doi: 10.3748/wjg.v10.i8.1171
Effects of autoantibodies against β1-adrenoceptor in hepatitis virus myocarditis on action potential and L-type Ca2+ currents
Kun Liu, Yu-Hua Liao, Zhao-Hui Wang, Shu-Li Li, Ming Wang, Ling-Lan Zeng, Ming Tang
Kun Liu, Yu-Hua Liao, Zhao-Hui Wang, Ming Wang, Department of Cardiology, Institute of Cardiology, Union Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430022, Hubei Province, China
Shu-Li Li, Ling-Lan Zeng, Department of Infectious Diseases, Union Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430022, Hubei Province, China
Ming Tang, Department of Physiology, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China
Author contributions: All authors contributed equally to the work.
Supported by the National Natural Science Foundation of China, NO.39970306
Correspondence to: Professor Yu-Hua Liao, Department of Cardiology, Institute of Cardiology, Union Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430022, Hubei Province, China. liaoyh27@hotmail.com
Telephone: +86-27-85726376
Received: November 12, 2003
Revised: December 3, 2003
Accepted: December 16, 2003
Published online: April 15, 2004
Abstract

AIM: To investigate the effects of autoantibodies against β1-adrenoceptor in hepatitis virus myocarditis on action potential and L-type Ca2+ currents.

METHODS: Fifteen samples of autoantibodies against β1-adrenoceptor positive sera of patients with hepatitis virus myocarditis were obtained and IgGs were purified by octanoic acid extraction. Binding of autoantibodies against β1-adrenoceptor to guinea pig cardiac myocytes was examined by immunofluorescence. Using the patch clamp technique, the effects on the action potential and ICa-L of guinea pig cardiac myocytes caused by autoantibodies against β1-adrenoceptor in the absence and presence of metoprolol were investigated. Cell toxicity was examined by observing cell morphology and permeability of cardiac myocytes to trypan blue.

RESULTS: The specific binding of autoantibodies against β1-adrenoceptor to guinea pig cardiomyocytes was observed. Autoantibodies against β1-adrenoceptor diluted at 1:80 prolonged APD20, APD50 and APD90 by 39.2%, 29.1% and 15.2% respectively, and only by 7.2%, 5.3% and 4.1% correspondingly in the presence of 1 μmol/L metoprolol. Autoantibodies against β1-adrenoceptor diluted at 1:80, 1:100 and 1:120 significantly increased the ICa-L peak current amplitude at 0 mV by 55.87 ± 4.39%, 46.33 ± 5.01% and 29.29 ± 4.97% in a concentration-dependent manner. In contrast, after blocking of β1-adrenoceptors (1 μmol/L metoprolol), autoantibodies against β1-adrenoceptor diluted at 1:80 induced a slight increase of ICa-L peak amplitude only by 6.81 ± 1.61%. A large number of cardiac myocytes exposed to high concentrations of autoantibodies against β1-adrenoceptor (1:80 and 1:100) were turned into rounded cells highly permeable to trypan blue.

CONCLUSION: Autoantibodies against β1-adrenoceptor may result in arrhythmias and/or impairment of myocardiums in HVM, which would be mediated by the enhancement of ICa-L.

Keywords: $[Keywords]