Title

Kv1.1 potassium channel subunit deficiency alters ventricular arrhythmia susceptibility, contractility, and repolarization

Authors

Krystle Trosclair, Department of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Man Si, Department of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Megan Watts, Department of Internal Medicine, Section of Cardiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Nicole M. Gautier, Department of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Niels Voigt, Institute of Pharmacology and Toxicology, University Medical Center Goettingen, Goettingen, Germany.
James Traylor, Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Miklós Bitay, Department of Cardiac Surgery, 2nd Department of Medicine and Cardiology Center, University of Szeged, Szeged, Hungary.
Istvan Baczko, Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary.
Dobromir Dobrev, Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany.
Kathryn A. Hamilton, Department of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Md Shenuarin Bhuiyan, Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Paari Dominic, Department of Internal Medicine, Section of Cardiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Edward Glasscock, Department of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.

Document Type

Article

Publication Date

1-1-2021

Abstract

Epilepsy-associated Kv1.1 voltage-gated potassium channel subunits encoded by the Kcna1 gene have traditionally been considered absent in heart, but recent studies reveal they are expressed in cardiomyocytes where they could regulate intrinsic cardiac electrophysiology. Although Kv1.1 now has a demonstrated functional role in atria, its role in the ventricles has never been investigated. In this work, electrophysiological, histological, and gene expression approaches were used to explore the consequences of Kv1.1 deficiency in the ventricles of Kcna1 knockout (KO) mice at the organ, cellular, and molecular levels to determine whether the absence of Kv1.1 leads to ventricular dysfunction that increases the risk of premature or sudden death. When subjected to intracardiac pacing, KO mice showed normal baseline susceptibility to inducible ventricular arrhythmias (VA) but resistance to VA under conditions of sympathetic challenge with isoproterenol. Echocardiography revealed cardiac contractile dysfunction manifesting as decreased ejection fraction and fractional shortening. In whole-cell patch-clamp recordings, KO ventricular cardiomyocytes exhibited action potential prolongation indicative of impaired repolarization. Imaging, histological, and transcript analyses showed no evidence of structural or channel gene expression remodeling, suggesting that the observed deficits are likely electrogenic due to Kv1.1 deficiency. Immunoblots of patient heart samples detected the presence of Kv1.1 at relatively high levels, implying that Kv1.1 contributes to human cardiac electrophysiology. Taken together, this work describes an important functional role for Kv1.1 in ventricles where its absence causes repolarization and contractility deficits but reduced susceptibility to arrhythmia under conditions of sympathetic drive.

Publication Source (Journal or Book title)

Physiological reports

First Page

e14702

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