Department of Mathematics, California Polytechnic State University, San Luis Obispo, California.
Department of Mathematics, University of Utah, Salt Lake City, Utah.
Biophys J. 2014 Feb 18;106(4):925-31. doi: 10.1016/j.bpj.2013.11.1117.
The effect of gap junctional coupling, sodium ion channel distribution, and extracellular conductivity on transverse conduction in cardiac tissue is explored using a microdomain model that incorporates aspects of the inhomogeneous cellular structure. The propagation velocities found in our model are compared to those in the classic bidomain model and indicate a strong ephaptic microdomain contribution to conduction depending on the parameter regime. We show that ephaptic effects can be quite significant in the junctional spaces between cells, and that the cell activation sequence is modified substantially by these effects. Further, we find that transverse propagation can be maintained by ephaptic effects, even in the absence of gap junctional coupling. The mechanism by which this occurs is found to be cablelike in that the junctional regions act like inverted cables. Our results provide insight into several recent experimental studies that indirectly indicate a mode of action potential propagation that does not rely exclusively on gap junctions.
使用包含不均匀细胞结构的微域模型探讨缝隙连接偶联、钠离子通道分布和细胞外电导率对心脏组织横向传导的影响。与经典双域模型相比，我们模型中发现的传播速度表明，根据参数范围，电突触微域对传导有很强的贡献。我们表明，电突触效应在细胞之间的连接空间中可能非常显著，并且这些效应大大改变了细胞的激活顺序。此外，我们发现即使没有缝隙连接偶联，电突触效应也可以维持横向传播。发生这种情况的机制被发现类似于电缆，即连接区的作用类似于倒转的电缆。我们的结果为最近的几项实验研究提供了一些见解，这些研究间接表明动作电位传播的模式并不完全依赖于缝隙连接。
