Dimitrova N
CLBA, Centre of Biology, Bulgarian Academy of Sciences, Sofia.
Gen Physiol Biophys. 1988 Dec;7(6):581-9.
A mathematical model was used to study transmembrane and extracellular potentials produced by active geometrically inhomogeneous excitable structures under conditions of propagation block. The structures were electrical analogues of intact or damaged unmyelinated nerve fibres, of the soma to axon transition, or of branching axons or dendrites. It was shown that: (1) damage to a cell is equivalent to the presence of a geometrical inhomogeneity, namely of a region of increased diameter; (2) propagation block caused by a geometrical inhomogeneity, results in; (a) a sharp decrease in the calculated transmembrane potential amplitude not only for the blocked region but also before it; (b) a considerable increase in the amplitude of both the negative phase of extracellular potentials at the points of the volume conductor preceding the blocked region and the first positive phase at points in the proximity of the region; (c) a more pronounced increase in the first positive phase amplitude at small radial distances, if the geometrical inhomogeneity is short compared with the length constant (gamma); (3) the membrane damage results in recording of potentials resembling "giant" ones.
使用数学模型研究了在传播阻滞条件下，由具有几何结构不均匀性的活性可兴奋结构产生的跨膜电位和细胞外电位。这些结构是完整或受损的无髓神经纤维、胞体到轴突过渡区、分支轴突或树突的电模拟物。结果表明：（1）细胞损伤等同于存在几何结构不均匀性，即直径增加的区域；（2）由几何结构不均匀性引起的传播阻滞会导致：（a）不仅在阻滞区域，而且在其之前，计算得到的跨膜电位幅度急剧下降；（b）在阻滞区域之前的体积导体点处，细胞外电位负相的幅度以及在该区域附近点处的第一个正相的幅度都显著增加；（c）如果几何结构不均匀性与长度常数（γ）相比很短，则在小径向距离处第一个正相幅度的增加更为明显；（3）膜损伤导致记录到类似“巨大”电位的电位。
