Roy G
Département de Physiologie, Université de Montréal, Québec, Canada.
Jpn J Physiol. 1994;44 Suppl 2:S37-42.
Cell volume regulation after swelling has been widely demonstrated and attributed to a loss of KCl in the external medium. But it was also shown in a few cell types that organic cell osmolytes, particularly amino acids, were contributing to volume regulation. These effluxes occurred through a diffusional type of transport. Electrophysiological experiments with patch-clamp electrodes have demonstrated the activation of selective K+ channels in parallel with chloride channels during volume regulation. These chloride channels appear much less selective for a large variety of anions. Many cell osmolytes, not only negatively charged but also neutral ones, are permeable through these channels. When the cells swell in hypotonic media, they loose amino acids and other neutral and negative osmolytes through these channels. It is possible that these channels in astrocytes play an important role in pathological conditions, e.g. brain ischemia, by releasing glutamate in the external medium and contributing to the damaging effect of glutamate in ischemia.
细胞肿胀后的体积调节已得到广泛证实，且归因于细胞外介质中氯化钾的流失。但在少数细胞类型中也发现，有机细胞渗透溶质，特别是氨基酸，对体积调节也有作用。这些流出是通过扩散型转运发生的。使用膜片钳电极进行的电生理实验表明，在体积调节过程中，选择性钾通道与氯离子通道同时被激活。这些氯离子通道对多种阴离子的选择性要低得多。许多细胞渗透溶质，不仅包括带负电荷的，还有中性的，都可以通过这些通道渗透。当细胞在低渗介质中肿胀时，它们会通过这些通道释放氨基酸以及其他中性和带负电荷的渗透溶质。星形胶质细胞中的这些通道可能在病理状况（如脑缺血）中发挥重要作用，即通过在细胞外介质中释放谷氨酸并加剧谷氨酸在缺血中的损伤作用。
