【摘要】 窦房结钙、膜钟控制自律性的新机制为揭示窦性心律失常提供了帮助,但目前钙钟动力学模型仅处于单细胞水平。本文构建了窦房结中心和边缘的单细胞模型,并按照指数形式改变中心到边缘细胞的膜电容、大小、电导及细胞间偶联电导,根据解剖结构构建了窦房结和心房二维非匀质模型。采用五点差分和有限元方法分别对组织内细胞网格和边界进行处理。通过分段构造试函数的方法确定不规则的组织边界。定量实验表明,构建的中心和边缘单细胞模型的动作电位在幅度、周期、最大舒张期电位以及上升速率等方面符合相关报道。钙钟和膜钟对主导起搏位置和除极速率的作用以及房性早搏对窦房结自律性的影响等定量研究也符合相关实验研究。本模型为深入探讨钙、膜钟在窦房结自律性中的相对作用以及与心房电活动的关系提供了帮助,同时可为构建三维窦房结和心房器官模型等奠定基础。更多还原

【Abstract】 The new mechanisms of automaticity controlled by the calcium and membrane clocks in sinoatrial node are helpful to revealing the sinus arrhythmia,but the present calcium dynamic model is only on the single cell level.In the present study,a central and peripheral single cell model was developed,and by exponentially changing the cell membrane capacitance,size,conductance and gap junction from the center to the periphery,a two-dimensional inhomogeneous sinus and atrial model was created on the basis of the anatomical structure.Five-point difference and finite element methods were used to process the internal grids and the borders.Irregular borders were defined by creating segment trial functions.Quantitative experiments suggested the consistency of the central and peripheral action potentials with related reports in amplitude,cycle length,maximum diastolic potential and upstroke velocity.Functions of the calcium and membrane clocks on the leading pacemaker site and upstroke velocity as well as the effects of the atrial premature beat on the sinus automaticity were also in good agreement with those in other studies.The developed model is helpful for deeply studying relative roles of the calcium and membrane clocks in automaticity and the relations with electrical activities in atrium.At the same time it will lay the foundation for building three-dimensional sinus and atrial organic models.更多还原