O'Neill W C
Renal Division, Department of Medicine, and Department of Physiology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Am J Physiol. 1999 May;276(5):C995-C1011. doi: 10.1152/ajpcell.1999.276.5.C995.
Research over the past 25 years has identified specific ion transporters and channels that are activated by acute changes in cell volume and that serve to restore steady-state volume. The mechanism by which cells sense changes in cell volume and activate the appropriate transporters remains a mystery, but recent studies are providing important clues. A curious aspect of volume regulation in mammalian cells is that it is often absent or incomplete in anisosmotic media, whereas complete volume regulation is observed with isosmotic shrinkage and swelling. The basis for this may lie in an important role of intracellular Cl- in controlling volume-regulatory transporters. This is physiologically relevant, since the principal threat to cell volume in vivo is not changes in extracellular osmolarity but rather changes in the cellular content of osmotically active molecules. Volume-regulatory transporters are also closely linked to cell growth and metabolism, producing requisite changes in cell volume that may also signal subsequent growth and metabolic events. Thus, despite the relatively constant osmolarity in mammals, volume-regulatory transporters have important roles in mammalian physiology.
过去25年的研究已经确定了特定的离子转运体和通道，它们会被细胞体积的急性变化激活，并有助于恢复稳态体积。细胞感知细胞体积变化并激活相应转运体的机制仍是一个谜，但最近的研究正在提供重要线索。哺乳动物细胞体积调节的一个奇特之处在于，在非等渗介质中，这种调节通常不存在或不完整，而在等渗性收缩和肿胀时则可观察到完全的体积调节。其基础可能在于细胞内氯离子在控制体积调节转运体方面的重要作用。这在生理上是相关的，因为体内对细胞体积的主要威胁不是细胞外渗透压的变化，而是渗透活性分子的细胞内含量的变化。体积调节转运体也与细胞生长和代谢密切相关，产生细胞体积的必要变化，这也可能为后续的生长和代谢事件发出信号。因此，尽管哺乳动物体内的渗透压相对恒定，但体积调节转运体在哺乳动物生理学中仍具有重要作用。
