Dexter F, Saidel G M, Rudy Y
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106.
J Theor Biol. 1989 Dec 19;141(4):505-14. doi: 10.1016/s0022-5193(89)80232-2.
Traditionally, the diffusion of acetylcholine (ACh) from a neuron to cardiac muscle in a neuroeffector junction has been modeled as radial diffusion from a nerve ending into a spherical homogeneous medium. Various microscopic structures in the heart may or may not influence the spatial distribution of ACh within neuroeffector junctions. To determine the effect of microscopic anatomy on the diffusion of ACh in neuroeffector junctions, we simulated the diffusion of ACh in a two-dimensional inhomogeneous geometry that was based on micrographs of neuroeffector junctions in the sinus node. ACh was released at sites adjacent to a neuron. Simulations showed that the times of peak concentration after release and the peak concentrations per se were distributed symmetrically above and below and to the right and left of the neuron, but not radially about the neuron. We conclude that the diffusion of ACh in the neuroeffector junctions of the sinus node cannot be predicted well by a mathematical model that assumes radial diffusion in a spherical and homogeneous medium.
传统上，神经效应器接头处乙酰胆碱（ACh）从神经元扩散至心肌的过程被模拟为从神经末梢向球形均匀介质的径向扩散。心脏中的各种微观结构可能会或可能不会影响神经效应器接头内ACh的空间分布。为了确定微观解剖结构对ACh在神经效应器接头中扩散的影响，我们在基于窦房结神经效应器接头显微照片的二维非均匀几何结构中模拟了ACh的扩散。ACh在与神经元相邻的部位释放。模拟结果表明，释放后峰值浓度出现的时间以及峰值浓度本身在神经元的上方和下方、右侧和左侧呈对称分布，但并非围绕神经元呈径向分布。我们得出结论，假设在球形均匀介质中进行径向扩散的数学模型无法很好地预测窦房结神经效应器接头中ACh的扩散。
