Schlue W R, Deitmer J W
J Exp Biol. 1980 Aug;87:23-43. doi: 10.1242/jeb.87.1.23.
Potassium-sensitive double-barrelled microelectrodes were used to measure the potassium content of extracellular spaces in leech ganglia, both intact and with the ganglion capsule opened. When the ganglion capsule was opened, the extracellular concentrations of potassium in the ganglion were similar to that of the bathing medium (4 mM). With intact ganglia the extracellular potassium concentration in the neuropile averaged 6.3 +/- 0.7 mM and in the nerve cell body region 5.8 +/- 0.6 mM. The potential measured in these parts of the ganglion was between +2 and -8 mV, averaging -1.9 mV. The change of potassium concentration in the extracellular spaces following increase or decrease in the concentration of potassium ions in the bath declined exponentially. This rate of change, which would be expected of a first-order diffusion process, was found in both the neuropile and the nerve cell body region. In a medium containing 5 x 10(-4) M ouabain, the potassium concentration in both parts of the ganglion increased transiently by an average of 3.8 +/- 1.0 mM in the neuropile and 1.2 +/- 0.4 mM in the nerve cell body region. Negatively charged polyelectrolytes in extracellular spaces of leech ganglia could affect the distribution of potassium ions to give a Donnan distribution. It is also possible, that the endothelial layer influences the extracellular potassium concentration in a ganglion under resting conditions.
使用钾敏感双管微电极测量完整的和打开神经节囊的水蛭神经节细胞外空间的钾含量。当打开神经节囊时，神经节内细胞外钾浓度与浴液中的相似（4 mM）。对于完整的神经节，神经纤维网中的细胞外钾浓度平均为6.3±0.7 mM，神经细胞体区域为5.8±0.6 mM。在神经节的这些部位测得的电位在+2至 -8 mV之间，平均为 -1.9 mV。浴液中钾离子浓度增加或减少后，细胞外空间中钾浓度的变化呈指数下降。这种变化速率是一级扩散过程所预期的，在神经纤维网和神经细胞体区域均有发现。在含有5×10⁻⁴ M哇巴因的培养基中，神经节两个部位的钾浓度均短暂升高，神经纤维网平均升高3.8±1.0 mM，神经细胞体区域升高1.2±0.4 mM。水蛭神经节细胞外空间中的带负电荷的聚电解质可能会影响钾离子的分布，从而产生唐南分布。在静息状态下，内皮细胞层也可能影响神经节内的细胞外钾浓度。
