Ca2+-activated Cl- current is antiarrhythmic by reducing both spatial and temporal heterogeneity of cardiac repolarization

Bence Hegyi; Balázs Horváth; Krisztina Váczi; Mónika Gönczi; Kornél Kistamás; Ferenc Ruzsnavszky; Roland Veress; Leighton T Izu; Ye Chen-Izu; Tamás Bányász; János Magyar; László Csernoch; Péter P Nánási; Norbert Szentandrássy

doi:10.1016/j.yjmcc.2017.06.014

Ca²⁺-activated Cl^- current is antiarrhythmic by reducing both spatial and temporal heterogeneity of cardiac repolarization

J Mol Cell Cardiol. 2017 Aug:109:27-37. doi: 10.1016/j.yjmcc.2017.06.014. Epub 2017 Jun 29.

Affiliations

¹ Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary; Department of Pharmacology, Genome and Biomedical Science Facility, University of California, Davis, 451 Health Sciences Drive, Rm 3503, Davis, CA 95616, USA.
² Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary; Faculty of Pharmacy, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary.
³ Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary.
⁴ Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary; MTA-DE Momentum, Laboratory of Protein Dynamics, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary.
⁵ Faculty of Pharmacy, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary.
⁶ Faculty of Pharmacy, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary; Department of Biomedical Engineering, Genome and Biomedical Science Facility, University of California, Davis, 451 Health Sciences Drive, Rm 2303, Davis, CA 95616, USA; Department of Internal Medicine, Division of Cardiology, Genome and Biomedical Science Facility, University of California, Davis, 451 Health Sciences Drive, Rm 6315, Davis, CA 95616, USA.
⁷ Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary; Division of Sport Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary.
⁸ Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary; Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary. Electronic address: nanasi.peter@med.unideb.hu.
⁹ Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary; Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Nagyerdei krt 98, P.O. Box 22, H-4012 Debrecen, Hungary.

Abstract

The role of Ca²⁺-activated Cl^- current (I_Cl(Ca)) in cardiac arrhythmias is still controversial. It can generate delayed afterdepolarizations in Ca²⁺-overloaded cells while in other studies incidence of early afterdepolarization (EAD) was reduced by I_Cl(Ca). Therefore our goal was to examine the role of I_Cl(Ca) in spatial and temporal heterogeneity of cardiac repolarization and EAD formation. Experiments were performed on isolated canine cardiomyocytes originating from various regions of the left ventricle; subepicardial, midmyocardial and subendocardial cells, as well as apical and basal cells of the midmyocardium. I_Cl(Ca) was blocked by 0.5mmol/L 9-anthracene carboxylic acid (9-AC). Action potential (AP) changes were tested with sharp microelectrode recording. Whole-cell 9-AC-sensitive current was measured with either square pulse voltage-clamp or AP voltage-clamp (APVC). Protein expression of TMEM16A and Bestrophin-3, ion channel proteins mediating I_Cl(Ca), was detected by Western blot. 9-AC reduced phase-1 repolarization in every tested cell. 9-AC also increased AP duration in a reverse rate-dependent manner in all cell types except for subepicardial cells. Neither I_Cl(Ca) density recorded with square pulses nor the normalized expressions of TMEM16A and Bestrophin-3 proteins differed significantly among the examined groups of cells. The early outward component of I_Cl(Ca) was significantly larger in subepicardial than in subendocardial cells in APVC setting. Applying a typical subepicardial AP as a command pulse resulted in a significantly larger early outward component in both subepicardial and subendocardial cells, compared to experiments when a typical subendocardial AP was applied. Inhibiting I_Cl(Ca) by 9-AC generated EADs at low stimulation rates and their incidence increased upon beta-adrenergic stimulation. 9-AC increased the short-term variability of repolarization also. We suggest a protective role for I_Cl(Ca) against risk of arrhythmias by reducing spatial and temporal heterogeneity of cardiac repolarization and EAD formation.

Keywords: Bestrophin-3; Ca(2+)-activated Cl(−) current; Early afterdepolarization; Short-term variability of repolarization; Spatial heterogeneity of repolarization; TMEM16A.

Publication types

Research Support, Non-U.S. Gov't
Research Support, N.I.H., Extramural

MeSH terms

Action Potentials / drug effects*
Animals
Anoctamin-1 / biosynthesis*
Anthracenes / pharmacology*
Arrhythmias, Cardiac / chemically induced
Arrhythmias, Cardiac / metabolism*
Arrhythmias, Cardiac / pathology
Bestrophins / biosynthesis*
Dogs
Myocytes, Cardiac / metabolism*
Myocytes, Cardiac / pathology

Substances

Anoctamin-1
Anthracenes
Bestrophins
9-anthroic acid