The effect of connexin40 deficiency on ventricular conduction system function during development.

AIMS The aim of this study was to characterize ventricular activation patterns in normal and connexin40-deficient mice in order to dissect the role of connexin40 in developing the conduction system. METHODS AND RESULTS We performed optical mapping of epicardial activation between ED9.5-18.5 and analysed ventricular activation patterns and times of left ventricular activation. Mouse embryos deficient for connexin40 were compared with normal and heterozygous littermates. Morphology of the primary interventricular ring (PIR) was delineated with the help of T3-LacZ transgene. Four major types of ventricular activation patterns characterized by primary breakthrough in different parts of the heart were detected during development: PIR, left ventricular apex, right ventricular apex, and dual right and left ventricular apices. Activation through PIR was frequently present at the early stages until ED12.5. From ED14.5, the majority of hearts showed dual left and right apical breakthrough, suggesting functionality of both bundle branches. Connexin40-deficient embryos showed initially a delay in left bundle branch function, but the right bundle branch block, previously described in the adults, was not detected in ED14.5 embryos and appeared only gradually with 80% penetrance at ED18.5. CONCLUSION The switch of function from the early PIR conduction pathway to the mature apex to base activation is dependent upon upregulation of connexin40 expression in the ventricular trabeculae. The early function of right bundle branch does not depend on connexin40. Quantitative analysis of normal mouse embryonic ventricular conduction patterns will be useful for interpretation of effects of mutations affecting the function of the cardiac conduction system.

[1]  James W. Smyth,et al.  Iroquois homeobox gene 3 establishes fast conduction in the cardiac His–Purkinje network , 2011, Proceedings of the National Academy of Sciences.

[2]  Robert H. Anderson,et al.  Developmental Origin, Growth, and Three-Dimensional Architecture of the Atrioventricular Conduction Axis of the Mouse Heart , 2010, Circulation research.

[3]  R. Kelly,et al.  Biphasic Development of the Mammalian Ventricular Conduction System , 2010, Circulation research.

[4]  David Sedmera,et al.  Effects of mechanical loading on early conduction system differentiation in the chick. , 2010, American journal of physiology. Heart and circulatory physiology.

[5]  Kenneth W. Spitzer,et al.  Blebbistatin Effectively Uncouples the Excitation-Contraction Process in Zebrafish Embryonic Heart , 2010, Cellular Physiology and Biochemistry.

[6]  John McAnally,et al.  Cx30.2 enhancer analysis identifies Gata4 as a novel regulator of atrioventricular delay , 2009, Development.

[7]  Nicholas S Peters,et al.  Connexin40 Imparts Conduction Heterogeneity to Atrial Tissue , 2008, Circulation research.

[8]  M. Blaha,et al.  Abnormal Myocardial and Coronary Vasculature Development in Experimental Hypoxia , 2008, Anatomical record.

[9]  R. Gourdie,et al.  Cardiac expression patterns of endothelin‐converting enzyme (ECE): Implications for conduction system development , 2008, Developmental dynamics : an official publication of the American Association of Anatomists.

[10]  I. Efimov,et al.  Application of blebbistatin as an excitation-contraction uncoupler for electrophysiologic study of rat and rabbit hearts. , 2007, Heart rhythm.

[11]  R. P. Thompson,et al.  Changes in activation sequence of embryonic chick atria correlate with developing myocardial architecture. , 2006, American journal of physiology. Heart and circulatory physiology.

[12]  Colin K. L. Phoon,et al.  Imaging Tools for the Developmental Biologist: Ultrasound Biomicroscopy of Mouse Embryonic Development , 2006, Pediatric Research.

[13]  I. Kubota,et al.  Rotigaptide (ZP123) improves atrial conduction slowing in chronic volume overload-induced dilated atria. , 2006, Basic & clinical pharmacology & toxicology.

[14]  Robert P. Thompson,et al.  Confocal Imaging of the Embryonic Heart: How Deep? , 2005, Microscopy and Microanalysis.

[15]  Z Wang,et al.  Development of the Right Ventricular Inflow Tract and Moderator Band: A Possible Morphological and Functional Explanation for Mahaim Tachycardia , 2005, Circulation research.

[16]  R. P. Thompson,et al.  Developmental transitions in electrical activation patterns in chick embryonic heart. , 2004, The anatomical record. Part A, Discoveries in molecular, cellular, and evolutionary biology.

[17]  G. Morley,et al.  Transitions in ventricular activation revealed by two-dimensional optical mapping. , 2004, The anatomical record. Part A, Discoveries in molecular, cellular, and evolutionary biology.

[18]  R. P. Thompson,et al.  Optical Mapping of Electrical Activation in the Developing Heart , 2004, Microscopy and Microanalysis.

[19]  Harold V M van Rijen,et al.  Architectural and functional asymmetry of the His-Purkinje system of the murine heart. , 2004, Cardiovascular research.

[20]  Tsutomu Matsushita,et al.  Gap junction alterations in human cardiac disease. , 2004, Cardiovascular research.

[21]  Robert P. Thompson,et al.  Spatiotemporal pattern of commitment to slowed proliferation in the embryonic mouse heart indicates progressive differentiation of the cardiac conduction system. , 2003, The anatomical record. Part A, Discoveries in molecular, cellular, and evolutionary biology.

[22]  Robert G. Gourdie,et al.  Hemodynamics Is a Key Epigenetic Factor in Development of the Cardiac Conduction System , 2003, Circulation research.

[23]  D. Roden,et al.  Development of the Cardiac Conduction System as Delineated by minK‐lacZ , 2003, Journal of cardiovascular electrophysiology.

[24]  S. Rivkees,et al.  Neuregulin-1 promotes formation of the murine cardiac conduction system , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[25]  M Delmar,et al.  Null Mutation of Connexin43 Causes Slow Propagation of Ventricular Activation in the Late Stages of Mouse Embryonic Development , 2001, Circulation research.

[26]  J Jalife,et al.  Visualization and functional characterization of the developing murine cardiac conduction system. , 2001, Development.

[27]  K. Willecke,et al.  Impaired Conduction in the Bundle Branches of Mouse Hearts Lacking the Gap Junction Protein Connexin40 , 2001, Circulation.

[28]  J. Jalife,et al.  High-Resolution Optical Mapping of the Right Bundle Branch in Connexin40 Knockout Mice Reveals Slow Conduction in the Specialized Conduction System , 2000, Circulation research.

[29]  W H Lamers,et al.  Abnormal Cardiac Conduction and Morphogenesis in Connexin40 and Connexin43 Double-Deficient Mice , 2000, Circulation research.

[30]  Robert H. Anderson,et al.  Developmental patterning of the myocardium , 2000, The Anatomical record.

[31]  R. Anderson,et al.  Formation of the atrioventricular septal structures in the normal mouse. , 1998, Circulation research.

[32]  W H Lamers,et al.  Development of the cardiac conduction system. , 1998, Circulation research.

[33]  K. Willecke,et al.  Reduced cardiac conduction velocity and predisposition to arrhythmias in connexin40-deficient mice , 1998, Current Biology.

[34]  David L. Paul,et al.  Mice lacking connexin40 have cardiac conduction abnormalities characteristic of atrioventricular block and bundle branch block , 1998, Current Biology.

[35]  D. M. Freeman,et al.  Changing activation sequence in the embryonic chick heart. Implications for the development of the His-Purkinje system. , 1997, Circulation research.

[36]  A. Moorman,et al.  Differential connexin distribution accommodates cardiac function in different species , 1995, Microscopy research and technique.

[37]  A. Moorman,et al.  Spatial distribution of “tissue‐specific” antigens in the developing human heart and skeletal muscle III. An immunohistochemical analysis of the distribution of the neural tissue antigen G1N2 in the embryonic heart; implications for the development of the atrioventricular conduction system , 1992, The Anatomical record.

[38]  A. Moorman,et al.  Spatial distribution of “tissue‐specific” antigens in the developing human heart and skeletal muscle. I. An immunohistochemical analysis of creatine kinase isoenzyme expression patterns , 1990, The Anatomical record.

[39]  T. Yada,et al.  Early events in development of electrical activity and contraction in embryonic rat heart assessed by optical recording. , 1985, The Journal of physiology.

[40]  C. E. Challice,et al.  The development of the conduction system in the mouse embryo heart. II. Histogenesis of the atrioventricular node and bundle. , 1977, Developmental biology.

[41]  C. E. Challice,et al.  The development of the conduction system in the mouse embryo heart. I. The first embryonic A-V conduction pathway. , 1977, Developmental biology.

[42]  K. Willecke,et al.  Connexin 30 is expressed in the mouse sino-atrial node and modulates heart rate. , 2010, Cardiovascular research.

[43]  I. Efimov,et al.  Electrophysiology and anatomy of embryonic rabbit hearts before and after septation. , 2005, American journal of physiology. Heart and circulatory physiology.

[44]  D. Gros,et al.  Gap junctional connexins in the developing mouse cardiac conduction system. , 2003, Novartis Foundation symposium.

[45]  熊井 まどか.  Loss of connexin45 causes a cushion defect in early cardiogenesis , 2000 .

[46]  N. Severs,et al.  Connexin45 (alpha 6) expression delineates an extended conduction system in the embryonic and mature rodent heart. , 1999, Developmental genetics.

[47]  A. Moorman,et al.  The development of the atrioventricular junction in the human heart. , 1996, Circulation research.

[48]  C. E. Challice,et al.  The development of the conduction system in the mouse embryo heart. , 1982, Developmental biology.