Affiliation:
1. From the Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY.
Abstract
Studies have characterized conduction velocity in the right and left bundle branches (RBB, LBB) of normal and genetically engineered mice. However, no information is available on the action potential characteristics of the specialized conduction system (SCS). We have used microelectrode techniques to characterize action potential properties of the murine SCS, as well as epicardial and endocardial muscle preparations for comparison. In the RBB, action potential duration at 50%, 70%, and 90% repolarization (APD
50,70,90
) was 6±0.7, 35±6, and 90±7 ms, respectively. Maximum upstroke velocity (dV/dt
max
) was 153±14 V/s, and conduction velocity averaged 0.85±0.2 m/s. APD
90
was longer in the Purkinje network of fibers (web) than in the RBB (
P
<0.01). Web APD
50
was longer in the left than in the right ventricle (
P
<0.05). Yet, web APD
90
was longer in the right than in the left ventricle (
P
<0.001). APD
50,70
was significantly longer in the endocardial than in the epicardial (
P
<0.001;
P
<0.003). APD
90
in the epicardial and endocardial was shorter than in the RBB (≈36 ms versus ≈100 ms). Spontaneous electrical oscillations in phase 2 of the SCS occasionally resulted in early afterdepolarizations. These results demonstrate that APDs in the murine SCS are significantly (≈2-fold) longer than in the myocardium and implicate the role of the murine SCS in arrhythmias. The differences should have important implications in the use of the mouse heart to study excitation, propagation, and arrhythmias.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Cardiology and Cardiovascular Medicine,Physiology
Cited by
44 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献