Attwell D, Cohen I, Eisner D
Proc R Soc Lond B Biol Sci. 1979 Nov 30;206(1163):145-61. doi: 10.1098/rspb.1979.0098.
For an isolated membrane, the resting (zero current) potential is stable is the slope conductance is positive, and is unstable if the slope conductance is negative. Recent work suggests that the properties of many preparations are influenced by the presence of an extracellular space that is not in good diffusive contact with the bulk extracellular fluid. Ionic current flow across the membrane changes the ion concentrations in this space. These concentration changes affect the stability of the membrane potential. Even if the slope conductance is negative, the presence of the extracellular space can confer stability on the resting potential. Conversely, even if the slope conductance is positive, the extracellular space can produce instability of the resting potential. Evaluation of the relevant parameters for cardiac Purkinje fibres, from published experimental data, suggests that concentration changes in the extracellular space may play a significant role in determining when an action potential is initiated.
对于一个孤立的膜，若斜率电导为正，静息（零电流）电位是稳定的；若斜率电导为负，则静息电位是不稳定的。最近的研究表明，许多标本的特性会受到一个与细胞外液主体扩散接触不良的细胞外间隙的影响。跨膜离子电流流动会改变这个间隙中的离子浓度。这些浓度变化会影响膜电位的稳定性。即使斜率电导为负，细胞外间隙的存在也能赋予静息电位稳定性。相反，即使斜率电导为正，细胞外间隙也会使静息电位产生不稳定性。根据已发表的实验数据对心脏浦肯野纤维的相关参数进行评估，结果表明细胞外间隙中的浓度变化在决定动作电位何时起始方面可能起重要作用。
