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Development. 2014 Nov;141(21):4149-57. doi: 10.1242/dev.110007. Epub 2014 Oct 1.

Reciprocal myocardial-endocardial interactions pattern the delay in atrioventricular junction conduction.

Author information

1
Cardiovascular Research Institute, University of California San Francisco, 555 Mission Bay Boulevard South, San Francisco, CA 94143-3120, USA.
2
Cardiovascular Research Institute, University of California San Francisco, 555 Mission Bay Boulevard South, San Francisco, CA 94143-3120, USA takashi.mikawa@ucsf.edu.

Abstract

Efficient blood flow depends on two developmental processes that occur within the atrioventricular junction (AVJ) of the heart: conduction delay, which entrains sequential chamber contraction; and valve formation, which prevents retrograde fluid movement. Defects in either result in severe congenital heart disease; however, little is known about the interplay between these two crucial developmental processes. Here, we show that AVJ conduction delay is locally assigned by the morphogenetic events that initiate valve formation. Our data demonstrate that physical separation from endocardial-derived factors prevents AVJ myocardium from becoming fast conducting. Mechanistically, this physical separation is induced by myocardial-derived factors that support cardiac jelly deposition at the onset of valve formation. These data offer a novel paradigm for conduction patterning, whereby reciprocal myocardial-endocardial interactions coordinate the processes of valve formation with establishment of conduction delay. This, in turn, synchronizes the electrophysiological and structural events necessary for the optimization of blood flow through the developing heart.

KEYWORDS:

Action potential; Atrioventricular junction; Conduction velocity diversification; Heart patterning; Optical mapping

PMID:
25273084
PMCID:
PMC4302900
DOI:
10.1242/dev.110007
[Indexed for MEDLINE]
Free PMC Article

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