Sep 16, 2004

Structure-function relationship in the AV junction

The Anatomical Record. Part A, Discoveries in Molecular, Cellular, and Evolutionary Biology
Igor R EfimovMark R Boyett


In the normal heart, the atrioventricular node (AVN) is part of the sole pathway between the atria and ventricles. Under normal physiological conditions, the AVN controls appropriate frequency-dependent delay of contractions. The AVN also plays an important role in pathology: it protects ventricles during atrial tachyarrhythmia, and during sinoatrial node failure an AV junctional pacemaker can drive the heart. Finally, the AV junction provides an anatomical substrate for reentry. Using fluorescent imaging with voltage-sensitive dyes and immunohistochemistry, we have investigated the structure-function relationship of the AV junction during normal conduction, reentry, and junctional rhythm. We identified molecular and structural heterogeneity that provides a substrate for the dual-pathway AVN conduction. We observed heterogeneity of expression of three isoforms of connexins: Cx43, Cx45, and Cx40. We identified the site of origin of junctional rhythm at the posterior extension of the AV node in 79% (n = 14) of the studied hearts. This structure was similar to the compact AV node as determined by morphologic and molecular investigations. In particular, both the posterior extension and the compact node express the pacemaking channe...Continue Reading

Mentioned in this Paper

Sinoatrial Node
Biochemical Pathway
GJA5 gene
GJA1 gene
Structure-Activity Relationship
GJC1 gene
Contraction (Finding)

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