scholarly journals The Relationship between Frequency Dependence of Action Potential Duration and the Expression of TRPC3 in Rabbit Ventricular Myocardium

2014 ◽  
Vol 33 (3) ◽  
pp. 646-656 ◽  
Author(s):  
Yong Wang ◽  
Mo-Si Chen ◽  
Hong-Chang Liu ◽  
Jun-Hua Xiao ◽  
Jia-Ling Wang
Keyword(s):  
Action Potential ◽  
Frequency Dependence ◽  
Action Potential Duration ◽  
Ventricular Myocardium ◽  
Rabbit Ventricular Myocardium ◽  
The Relationship

scholarly journals Effect of activation sequence on transmural patterns of repolarization and action potential duration in rabbit ventricular myocardium

2010 ◽  
Vol 299 (6) ◽  
pp. H1812-H1822 ◽  
Author(s):  
Rachel C. Myles ◽  
Olivier Bernus ◽  
Francis L. Burton ◽  
Stuart M. Cobbe ◽  
Godfrey L. Smith
Keyword(s):  
Action Potential ◽  
Action Potential Duration ◽  
Single Cells ◽  
Ventricular Myocardium ◽  
Left Ventricular ◽  
Isolated Cells ◽  
Electrophysiological Properties ◽  
Relative Contribution ◽  
Rabbit Ventricular Myocardium ◽  
Transmural Heterogeneity

Although transmural heterogeneity of action potential duration (APD) is established in single cells isolated from different tissue layers, the extent to which it produces transmural gradients of repolarization in electrotonically coupled ventricular myocardium remains controversial. The purpose of this study was to examine the relative contribution of intrinsic cellular gradients of APD and electrotonic influences to transmural repolarization in rabbit ventricular myocardium. Transmural optical mapping was performed in left ventricular wedge preparations from eight rabbits. Transmural patterns of activation, repolarization, and APD were recorded during endocardial and epicardial stimulation. Experimental results were compared with modeled data during variations in electrotonic coupling. A transmural gradient of APD was evident during endocardial stimulation, which reflected differences previously seen in isolated cells, with the longest APD at the endocardium and the shortest at the epicardium (endo: 165 ± 5 vs. epi: 147 ± 4 ms; P < 0.05). During epicardial stimulation, this gradient reversed (epi: 162 ± 4 vs. endo: 148 ± 6 ms; P < 0.05). In both activation sequences, transmural repolarization followed activation and APD shortened along the activation path such that significant transmural gradients of repolarization did not occur. This correlation between transmural activation time and APD was recapitulated in simulations and varied with changes in intercellular coupling, confirming that it is mediated by electrotonic current flow between cells. These data suggest that electrotonic influences are important in determining the transmural repolarization sequence in rabbit ventricular myocardium and that they are sufficient to overcome intrinsic differences in the electrophysiological properties of the cells across the ventricular wall.

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