Impulse Propagation Through the Cardiac Junctional Regions of the Axolotl and the Turtle

Alanís, J; Benítez, Daisy; López, Enrique; Martı́nez-Palomo, Adolfo

doi:10.2170/jjphysiol.23.149

Cited by 15 publications

(12 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The electrical configuration of the amphibian heart is remarkably similar to that of the fish heart (2,193). The fastest conduction velocities are observed in the atria and the slowest in the bulbar region.…”

Section: E the Electrical Configuration Of The Chamber Heartmentioning

confidence: 75%

See 1 more Smart Citation

Cardiac Chamber Formation: Development, Genes, and Evolution

Moorman

Christoffels

2003

Physiological Reviews

641

526

View full text Add to dashboard Cite

Moorman, Antoon F. M., and Vincent M. Christoffels. Cardiac Chamber Formation: Development, Genes, and Evolution. Physiol Rev 83: 1223-1267, 2003; 10.1152/physrev.00006.2003.—Concepts of cardiac development have greatly influenced the description of the formation of the four-chambered vertebrate heart. Traditionally, the embryonic tubular heart is considered to be a composite of serially arranged segments representing adult cardiac compartments. Conversion of such a serial arrangement into the parallel arrangement of the mammalian heart is difficult to understand. Logical integration of the development of the cardiac conduction system into the serial concept has remained puzzling as well. Therefore, the current description needed reconsideration, and we decided to evaluate the essentialities of cardiac design, its evolutionary and embryonic development, and the molecular pathways recruited to make the four-chambered mammalian heart. The three principal notions taken into consideration are as follows. 1) Both the ancestor chordate heart and the embryonic tubular heart of higher vertebrates consist of poorly developed and poorly coupled “pacemaker-like” cardiac muscle cells with the highest pacemaker activity at the venous pole, causing unidirectional peristaltic contraction waves. 2) From this heart tube, ventricular chambers differentiate ventrally and atrial chambers dorsally. The developing chambers display high proliferative activity and consist of structurally well-developed and well-coupled muscle cells with low pacemaker activity, which permits fast conduction of the impulse and efficacious contraction. The forming chambers remain flanked by slowly proliferating pacemaker-like myocardium that is temporally prevented from differentiating into chamber myocardium. 3) The trabecular myocardium proliferates slowly, consists of structurally poorly developed, but well-coupled, cells and contributes to the ventricular conduction system. The atrial and ventricular chambers of the formed heart are activated and interconnected by derivatives of embryonic myocardium. The topographical arrangement of the distinct cardiac muscle cells in the forming heart explains the embryonic electrocardiogram (ECG), does not require the invention of nodes, and allows a logical transition from a peristaltic tubular heart to a synchronously contracting four-chambered heart. This view on the development of cardiac design unfolds fascinating possibilities for future research.

show abstract

Section: E the Electrical Configuration Of The Chamber Heartmentioning

confidence: 75%

“…This flow can be con- 2 Reynolds number (Re) is a unitless number representative of the tendency of a liquid (or gas) to become turbulent. It is proportional to the velocity of flow and to the density, and inversely proportional to the viscosity.…”

Section: B Cardiac Looping Changing Blood Flows and Chamber Formationmentioning

confidence: 99%

Cardiac Chamber Formation: Development, Genes, and Evolution

Moorman

Christoffels

2003

Physiological Reviews

641

526

View full text Add to dashboard Cite

show abstract

“…6,50,51 Although the term "specialized cardiac tissue" seems at first glance surprising in view of the current histological, molecular, and electrophysiological data, one should realize that this terminology originates from the beginning of this century and is based on phylogenetic considerations about the adult hearts of lower vertebrates, where these areas have been dubbed "specialized" and have been attributed sphincter-like functions. 2,123 The low conduction velocities measured in the flanking segments of the embryonic mammalian heart are amazingly similar to those measured in the junctional areas of the amphibian heart, 124 indicating that the basic architecture of the vertebrate embryonic heart follows a phylogenetically old pattern.…”

Section: Segments and Ringsmentioning

confidence: 75%

Development of the Cardiac Conduction System

Moorman

Jong

Denyn

et al. 1998

Circulation Research

233

184

View full text Add to dashboard Cite

“…More importantly perhaps, cardiomyocytes from the same region of mud turtles ( Kinosternon spp.) have action potentials with a much slower rate of depolarization and this may explain the atrioventricular delay regardless of the underlying architecture (Alanís et al ., ; Martínez‐Palomo & Alanís, ). Also, we have shown recently that the fast‐propagating gap junction protein Cx40 is absent from the atrioventricular canal in Anolis carolinensis and A. sagrei , like in the atrioventricular node of mammals and birds (Jensen et al ., ).…”

Section: Reptile Heartsmentioning

confidence: 99%

Structure and function of the hearts of lizards and snakes

2013

View full text Add to dashboard Cite

With approximately 7000 species, snakes and lizards, collectively known as squamates, are by far the most species-rich group of reptiles. It was from reptile-like ancestors that mammals and birds evolved and squamates can be viewed as phylogenetically positioned between them and fishes. Hence, their hearts have been studied for more than a century yielding insights into the group itself and into the independent evolution of the fully divided four-chambered hearts of mammals and birds. Structurally the heart is complex and debates persist on rudimentary issues such as identifying structures critical to understanding ventricle function. In seeking to resolve these controversies we have generated three-dimensional (3D) models in portable digital format (pdf) of the anaconda and anole lizard hearts ('typical' squamate hearts) and the uniquely specialized python heart with comprehensive annotations of structures and cavities. We review the anatomy and physiology of squamate hearts in general and emphasize the unique features of pythonid and varanid lizard hearts that endow them with mammal-like blood pressures. Excluding pythons and varanid lizards it is concluded that the squamate heart has a highly consistent design including a disproportionately large right side (systemic venous) probably due to prevailing pulmonary bypass (intraventricular shunting). Unfortunately, investigations on rudimentary features are sparse. We therefore point out gaps in our knowledge, such as the size and functional importance of the coronary vasculature and of the first cardiac chamber, the sinus venosus, and highlight areas with implications for vertebrate cardiac evolution.

show abstract

Impulse Propagation Through the Cardiac Junctional Regions of the Axolotl and the Turtle

Cited by 15 publications

References 17 publications

Cardiac Chamber Formation: Development, Genes, and Evolution

Cardiac Chamber Formation: Development, Genes, and Evolution

Development of the Cardiac Conduction System

Structure and function of the hearts of lizards and snakes

Contact Info

Product

Resources

About