Related Experiment Video
Updated: Jul 2, 2026

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
Abnormal cardiac repolarization and impulse initiation in German shepherd dogs with inherited ventricular arrhythmias
E A Sosunov1, E P Anyukhovsky, A Shvilkin
1Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA.
Objective:
We tested the hypothesis that delayed afterdepolarization (DAD)-associated rhythms in German shepherd dogs with reduced anteroseptal left ventricular (LV) sympathetic innervation derive from abnormal beta-adrenergic receptor effector coupling.
Methods And Results:
In anteroseptal LV midmyocardium of afflicted dogs, beta-receptor density was greater than that in normal dogs (P < .05), with affinity being equal in both groups. Basal and maximum isoproterenol (ISO) stimulated adenylyl cyclase activity of anteroseptal LV of afflicted dogs was greater than that in normal dogs (P < .05). Isolated anteroseptal M cell preparations of afflicted dogs studied with microelectrodes showed abnormal lengthening, rather than shortening of action potential duration in response to ISO, as well as a 61% incidence of 10(-7) mol/l ISO-induced triggered activity as compared to 12% in normals (P < .05). In contrast, there was no difference between afflicted and control dogs in triggered activity, beta-receptors or adenylyl cyclase activity in a normally innervated region of the ventricles.
Conclusion:
In this model there is an increase in beta-receptor density and beta-adrenergic stimulation of adenylyl cyclase and of triggered activity in anteroseptal myocardium but not in a normally innervated region of the heart. Hence, abnormal beta-adrenergic signal transduction appears associated with the neural abnormality identified in dogs with inherited VT.
More Related Videos
12:15Tissue Preparation Techniques for Contrast-Enhanced Micro Computed Tomography Imaging of Large Mammalian Cardiac Models with Chronic Disease
Published on: February 8, 2022
06:46Implantation of Electroencephalogram and Electrocardiogram Telemetry Devices in Neonatal Rabbit Kits
Published on: February 28, 2025
Related Concept Videos
Electrophysiology of Normal Cardiac Rhythm
Mechanism of Cardiac Arrhythmias
Disturbances in Heart Rhythm
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...
Dysrhythmias I: Introduction
Dysrhythmias IV: Characteristics of Bradyarrhythmias
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias