缝隙连接对组织水平心脏电生理学影响的模型化
Modelling the effect of gap junctions on tissue-level cardiac electrophysiology
摘要：
当模拟组织水平的心脏电生理学，连续近似的离散细胞水平的方程用于保持计算的易处理性。最常用的模型之一是由bidomain方程表示，其推导依赖于均匀化技术来构建离散模型的适当近似。这种推导并没有明确说明连接一个细胞与另一个细胞的间隙连接的存在。它已被实验[Rohr，Bavasc。Res. 2004]，这些缝隙连接对动作电位的传播具有显著影响，特别是当波的上行通过缝隙连接时。在本文中，我们明确包括缝隙连接在一个二维离散模型的心脏电生理学，和相应的连续模型，在一个简化的细胞几何形状。使用这些模型，我们比较使用连续和离散系统的模拟结果。我们看到，当动作电位通过缝隙连接时，它的形式不能使用连续模型复制，并且当引入缝隙连接时，动作电位的潜在传播速度在模型之间不再匹配。此外，离散模拟的结果与Rohr 2004中所示的特征相匹配。从这一点上，我们建议，一个混合模型-一个离散系统的动作电位的上升，和一个连续的系统在其他地方-可能会给出一个更准确的描述心脏电生理。
英文摘要：
When modelling tissue-level cardiac electrophysiology, continuum approximations to the discrete cell-level equations are used to maintain computational tractability. One of the most commonly used models is represented by the bidomain equations, the derivation of which relies on a homogenisation technique to construct a suitable approximation to the discrete model. This derivation does not explicitly account for the presence of gap junctions connecting one cell to another. It has been seen experimentally [Rohr, Cardiovasc. Res. 2004] that these gap junctions have a marked effect on the propagation of the action potential, specifically as the upstroke of the wave passes through the gap junction. In this paper we explicitly include gap junctions in a both a 2D discrete model of cardiac electrophysiology, and the corresponding continuum model, on a simplified cell geometry. Using these models we compare the results of simulations using both continuum and discrete systems. We see that the form of the action potential as it passes through gap junctions cannot be replicated using a continuum model, and that the underlying propagation speed of the action potential ceases to match up between models when gap junctions are introduced. In addition, the results of the discrete simulations match the characteristics of those shown in Rohr 2004. From this, we suggest that a hybrid model -- a discrete system following the upstroke of the action potential, and a continuum system elsewhere -- may give a more accurate description of cardiac electrophysiology.
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