Molecular dissection of cardiac repolarization by in vivo Kv4.3 gene transfer

Uta C. Hoppe, Eduardo Marbán, David C. Johns

Research output: Contribution to journalArticlepeer-review

Abstract

Heart failure leads to marked suppression of the Ca2+-independent transient outward current (I(to1)), but it is not clear whether I(to1) downregulation suffices to explain the concomitant action potential prolongation. To investigate the role of I(to1) in cardiac repolarization while circumventing culture-related action potential alterations, we injected adenovirus vectors in vivo to overexpress or to suppress I(to1) in guinea pigs and rats, respectively. Myocytes were isolated 72 hours after intramyocardial injection and stimulation of the ecdysone-inducible vectors with intraperitoneal injection of an ecdysone analog. Kv4.3-infected guinea pig myocytes exhibited robust transient outward currents. Increasing density of I(to1) progressively depressed the plateau potential in Kv4.3-infected guinea pig myocytes and abbreviated action potential duration (APD). In vivo infection with a dominant-negative Kv4.3-W362F construct suppressed peak I(to1) in rat ventriculocytes, elevated the plateau height, significantly prolonged the APD, and resulted in a prolongation by about 30% of the QT interval in surface electrocardiogram recordings. These results indicate that I(to1) plays a crucial role in setting the plateau potential and overall APD, supporting a causative role for suppression of this current in the electrophysiological alterations of heart failure. The electrocardiographic findings indicate that somatic gene transfer can be used to create gene- specific animal models of the long QT syndrome.

Original languageEnglish (US)
Pages (from-to)1077-1084
Number of pages8
JournalJournal of Clinical Investigation
Volume105
Issue number8
StatePublished - Apr 2000

ASJC Scopus subject areas

  • Medicine(all)

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