scholarly journals Measurement of cAMP in the cardiac conduction system of rats.

1995 ◽  
Vol 43 (6) ◽  
pp. 601-605 ◽  
Author(s):  
A Sugiyama ◽  
S McKnite ◽  
P Wiegn ◽  
K G Lurie
Keyword(s):  
Atrioventricular Node ◽  
Conduction System ◽  
Cardiac Conduction ◽  
Cardiac Conduction System ◽  
Camp Production ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
His Bundle ◽  
Freeze Dried ◽  
Camp Levels

To characterize differences in regional cAMP production in the cardiac conduction system, 18 rats were anesthetized with pentobarbital (65 mg/kg IP) and randomized into a control (n = 9) and a stimulated group (n = 9). The stimulated group received aminophylline (20 mg/kg SC) and isoproterenol (16 micrograms/kg SC). The concentration of cAMP in freeze-dried, micro dissected pieces (1-3 micrograms) of cardiac tissue was measured using a new microanalytical method. The cAMP contents in right atrium, atrioventricular node, His bundle, and left ventricle (fmol/microgram dry weight, mean +/- SE) were 38.9 +/- 2.5, 39.0 +/- 4.3, 46.4 +/- 6.1, and 41.4 +/- 3.3 in controls and 72.9 +/- 6.7, 86.1 +/- 2.9, 115.0 +/- 11.5, and 79.5 +/- 7.3 in the stimulated group, respectively. Basal cAMP levels were similar throughout the heart, whereas isoproterenol increased cAMP levels in all regions (p < 0.01). Furthermore, cAMP levels in His bundle, after isoproterenol, were higher than in any other region (p < 0.05). These results demonstrate that: (a) cAMP can be measured in discrete portions of the cardiac conduction system; (b) there are significant regional differences of beta-adrenergic control in the cardiac conduction system; and (c) cAMP production after beta-adrenergic stimulation was lower than expected in the AV nodal region, based on previously described beta-adrenoceptor density measurements.

Abstract 1462: Lineage Analysis of Mesp1 Expressing Cells in Cardiac Conduction System

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Reza Rafie ◽  
Amir R Hajrasouliha ◽  
Sina Tavakoli ◽  
Kamal Kotak ◽  
Mohammad Pashmforoush
Keyword(s):  
Sinoatrial Node ◽  
Atrioventricular Node ◽  
Conduction System ◽  
Cardiac Conduction ◽  
Cardiac Conduction System ◽  
Transgenic Mouse Line ◽  
His Bundle ◽  
Reporter Mice ◽  
A Minor ◽  
Lineage Analysis

Mesp1 is the earliest transcription factor detected in cardiac precursor cells considered to play a key role in their early specification. The lineage analysis, using Mesp1- Cre transgenic mouse line, has shown that there is a minor contribution of Mesp1 non-expressing cells to the formation of ventricular conduction system. The purpose of the present study is to evaluate the contribution of Mesp1 -expressing and non-expressing cells to the development of sinoatrial node, atrioventricular node and His bundle in embryonic, neonatal and adult heart. In this study, the contribution of Mesp1 -expressing cells was evaluated by a lineage analysis using the cross of Mesp1 -Cre and ROSA26R reporter mice. Different components of the cardiac conduction system were identified by a combination of histological (hematoxylin/eosin), acetylcholinesterase, and immunofluorescent stainings for specific markers (HCN4 and connexin40). Sinoatrial and atrioventricular nodes as well as His bundle are derived almost exclusively from Mesp1- expressing cells as evident by β-gal activity. The contribution of Mesp1 non-expressing cells becomes prominent, though still less than Mesp1 -expressing cells, in the distal components of cardiac conduction system (i.e. bundle branches). This pattern was consistent in embryonic and neonatal stages as well as adult hearts. Unlike the distal components of cardiac conduction system, which is composed of a mixed population of Mesp1 -expressing and non-expressing cells, sinoatrial node, atrioventricular node and His bundle are derived almost exclusively from Mesp1 -expressing cells.

Development of the cardiac conduction system

ESC CardioMed ◽  
2018 ◽  
pp. 49-52
Author(s):  
Jan Hendrik van Weerd ◽  
Vincent M. Christoffels
Keyword(s):  
Regulatory Networks ◽  
Atrioventricular Node ◽  
Ventricular Myocardium ◽  
Conduction System ◽  
Cardiac Conduction ◽  
Cardiac Conduction System ◽  
Cellular Mechanisms ◽  
Fibre Network ◽  
Electrical Impulses ◽  
And Function

The contraction of the heart is orchestrated by the components of the cardiac conduction system (CCS), which initiate and propagate the electrical impulses to coordinately activate the cardiac chambers. In the adult heart, the impulse is generated in the sinoatrial node and activates the atrial myocardium. Slow conduction of the impulse through the atrioventricular node allows for emptying of the atria and filling of the ventricles prior to ventricular contraction. Subsequent fast conduction through the atrioventricular bundle, bundle branches, and Purkinje fibre network activates the ventricular myocardium and causes the ventricles to contract. The development and function of the CCS involves complex regulatory networks of transcription factors acting in stage-, tissue-, and dose-dependent manners. Disrupted function or expression of these factors might lead to impaired development or function of the CCS components, associated with heart failure and sudden death. It is therefore crucial to understand the molecular and cellular mechanisms controlling the complex regulation of CCS development. This chapter summarizes current insight in the development and function of the different compartments of the CCS, and discusses the transcriptional networks underlying these processes.

Development of the cardiac conduction system

ESC CardioMed ◽  
2018 ◽  
pp. 49-52
Author(s):  
Jan Hendrik van Weerd ◽  
Vincent M. Christoffels
Keyword(s):  
Regulatory Networks ◽  
Atrioventricular Node ◽  
Ventricular Myocardium ◽  
Conduction System ◽  
Cardiac Conduction ◽  
Cardiac Conduction System ◽  
Cellular Mechanisms ◽  
Fibre Network ◽  
Electrical Impulses ◽  
And Function

The contraction of the heart is orchestrated by the components of the cardiac conduction system (CCS), which initiate and propagate the electrical impulses to coordinately activate the cardiac chambers. In the adult heart, the impulse is generated in the sinoatrial node and activates the atrial myocardium. Slow conduction of the impulse through the atrioventricular node allows for emptying of the atria and filling of the ventricles prior to ventricular contraction. Subsequent fast conduction through the atrioventricular bundle, bundle branches, and Purkinje fibre network activates the ventricular myocardium and causes the ventricles to contract. The development and function of the CCS involves complex regulatory networks of transcription factors acting in stage-, tissue-, and dose-dependent manners. Disrupted function or expression of these factors might lead to impaired development or function of the CCS components, associated with heart failure and sudden death. It is therefore crucial to understand the molecular and cellular mechanisms controlling the complex regulation of CCS development. This chapter summarizes current insight in the development and function of the different compartments of the CCS, and discusses the transcriptional networks underlying these processes.

scholarly journals SEM, TEM, and IHC Analysis of the Sinus Node and Its Implications for the Cardiac Conduction System

2013 ◽  
Vol 2013 ◽  
pp. 1-6
Author(s):  
D. Mandrioli ◽  
F. Ceci ◽  
T. Balbi ◽  
C. Ghimenton ◽  
G. Pierini
Keyword(s):  
Electron Microscopy ◽  
Sinus Node ◽  
Atrioventricular Node ◽  
Definite Description ◽  
Conduction System ◽  
Cardiac Conduction ◽  
Cardiac Conduction System ◽  
Ordered Structure ◽  
Healthy Individuals ◽  
Optical And Electron Microscopy

More than 100 years after the discovery of the sinus node (SN) by Keith and Flack, the function and structure of the SN have not been completely established yet. The anatomic architecture of the SN has often been described as devoid of an organized structure; the origin of the sinus impulse is still a matter of debate, and a definite description of the long postulated internodal specialized tract conducting the impulse from the SN to the atrioventricular node (AVN) is still missing. In our previously published study, we proposed a morphologically ordered structure for the SN. As a confirmation of what was presented then, we have added the results of additional observations regarding the structural particularities of the SN. We investigated the morphology of the sinus node in the human hearts of healthy individuals using histochemical, immunohistochemical, optical, and electron microscopy (SEM, TEM). Our results confirmed that the SN presents a previously unseen highly organized architecture.

Simulation of Heartbeat Dynamics: A Nonlinear Model

1998 ◽  
Vol 08 (08) ◽  
pp. 1725-1731 ◽  
Author(s):  
Maria G. Signorini ◽  
Diego di Bernardo
Keyword(s):  
Mathematical Modeling ◽  
Simple Structure ◽  
Nonlinear Differential Equations ◽  
Atrioventricular Node ◽  
Nonlinear Oscillators ◽  
Conduction System ◽  
Cardiac Conduction ◽  
Cardiac Conduction System ◽  
Real Situation ◽  
Cardiac Dynamics

The mathematical modeling of biological systems has proven to be a valuable tool by allowing experiments which would otherwise be unfeasible in a real situation. In this work we propose a system of nonlinear differential equations describing the macroscopic behavior of the cardiac conduction system. The model describes the interactoin between the SinoAtrial and AtrioVentricular node. Its very simple structure consists of two nonlinear oscillators resistively coupled. The numerical analysis detects different kinds of bifurcations whose pathophysiological meanings are discussed. Moreover, the model is able to classify different pathologies, such as several classes of arrhythmic events, as well as to suggest hypothesis on the mechanisms that induce them. These results also show that the mechanisms generating the heartbeat obey complex laws. The model provides a wuite complete description of different pathological phenomena and its simplicity can be exploited for further studies on the control of cardiac dynamics.

Electrophysiologic Study of the Conduction System in Normal Children

PEDIATRICS ◽  
1977 ◽  
Vol 60 (6) ◽  
pp. 858-863
Author(s):  
Nigel K. Roberts ◽  
Paul C. Gillette
Keyword(s):  
Recovery Time ◽  
Sinus Node ◽  
Atrioventricular Node ◽  
Conduction System ◽  
Cardiac Conduction ◽  
Purkinje Fiber ◽  
Normal Children ◽  
Electrophysiologic Study ◽  
His Bundle ◽  
The Mean

Values for cardiac conduction intervals obtained from normal children are reported so that the data will be available for comparison with patients who are suspected of having abnormalities. Sinus node recovery time correlated linearly with the resting PP interval. The mean intra-atnal conduction was considerably shorter in children (&lt; 25 msec) than in adults (42 msec). The atrioventricular node had similar electrophysiologic properties in the child and adult. With aging, the His bundle to Purkinje fiber time increased significantly (P &lt; .01).

Cartilaginous Metaplasia Involving the Atrioventricular Node and Bundle of His Contributing to Sudden Early Neonatal Death

2019 ◽  
Vol 23 (4) ◽  
pp. 312-316
Author(s):  
Linda J Szymanski ◽  
Linda M Ernst
Keyword(s):  
Perinatal Death ◽  
Atrioventricular Node ◽  
Conduction System ◽  
Cardiac Conduction ◽  
Cardiac Conduction System ◽  
Early Neonatal Death ◽  
Av Node ◽  
Fibrous Body ◽  
Bundle Of His ◽  
Peripartum Period

Cartilaginous metaplasia involving the atrioventricular (AV) node is an uncommon entity that may cause sudden cardiac death secondary to dysrhythmias. We report 2 autopsy cases of full-term male newborns: 1 stillborn and 1 live-born, with antemortem bradycardia who died in the peripartum period. An examination of the cardiac conduction system in both cases demonstrated extensive cartilaginous metaplasia of the central fibrous body and involvement of the AV node and bundle of His. The cases highlight the recognition of cardiac conduction system anomalies as a cause of sudden perinatal death. In cases of perinatal death with preceding arrhythmia, postmortem sections of the cardiac conduction system are recommended to examine for cardiac conduction system anomaly.

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