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(Circulation Research. 2006;98:1237.)
© 2006 American Heart Association, Inc.

Editorials

Transmural Gradients of Repolarization and Excitation–Contraction Coupling in Mouse Ventricle

Céline Fiset, Wayne R. Giles

From the Research Center (C.F.), Montreal Heart Institute, Quebec, Canada; and the Departments of Bioengineering and Medicine (W.R.G.), University of California San Diego, La Jolla, Calif.

Correspondence to Wayne R. Giles, PhD, Professor, Departments of Bioengineering and Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412. E-mail wgiles@bioeng.ucsd.edu

See related article, pages 1306–1313

Key Words: transmural repolarization • Kv4.2/4.3K channel beta subunits

An extract of the first 250 words of the full text is provided, because this article has no abstract.

The effects of changes in action potential waveform on excitation–contraction coupling in mammalian ventricle were first identified almost 40 years ago.¹ Many important details concerning the relationship between action potential duration and tension development have been elucidated.² Recent work has demonstrated significant effects on the intracellular Ca transient and excitation–contraction coupling of early repolarization of the action potential, which is strongly regulated by a Ca²⁺-independent transient outward K⁺ current denoted I_to.^3–6 The molecular physiology and some aspects of the pharmacology of this current are now quite well understood, based, in part, on a series of comprehensive articles from the Nerbonne et al,^7,8 Strauss and Campbell,⁹ and others.⁶ Interestingly, a somewhat similar transient outward K⁺ current is expressed in neurons¹⁰ and in selected regions near the intraventricular septum of mammalian hearts.^11–13

One of the most striking features of the transient outward K⁺ current in mammalian ventricle is the difference in its transmural expression, with significantly higher expression levels in epi- than in endocardium¹⁴ (see also references ^{8, 9, 11}). The basis for this transmural heterogeneity, and also for the higher levels of expression in the right ventricle compared with the left, continues to be a topic of intense investigation. Significant new information and plausible working hypotheses for the way in which this heterogeneity can regulate excitation–contraction coupling are a focus of work from the laboratory of Santana et al.¹⁵ Their most recent article is published in this issue of Circulation Research.¹⁶ This article provides new evidence for the ways in . . . [Full Text of this Article]

Related Article:

Differential Calcineurin/NFATc3 Activity Contributes to the I_to Transmural Gradient in the Mouse Heart

Charles F. Rossow, Keith W. Dilly, and Luis F. Santana
Circ. Res. 2006 98: 1306-1313. [Abstract] [Full Text] [PDF]

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