Chamberlin M E, Strange K
Department of Zoological and Biomedical Sciences, Ohio University, Athens 45701.
Am J Physiol. 1989 Aug;257(2 Pt 1):C159-73. doi: 10.1152/ajpcell.1989.257.2.C159.
A variety of organisms and cell types spanning the five taxonomic kingdoms are exposed, either naturally or through experimental means, to osmotic stresses. A common physiological response to these challenges is maintenance of cell volume through changes in the concentration of intracellular inorganic and organic solutes, collectively termed osmolytes. Research on the mechanisms by which the concentration of these solutes is regulated has proceeded along several experimental lines. Extensive studies on osmotically activated ion transport pathways have been carried out in vertebrate cells and tissues. Much of our knowledge on organic osmolytes has come from investigations on invertebrates, bacteria, and protists. The relative simplicity of bacterial genetics has provided a powerful and elegant tool to explore the modifications of gene expression during volume regulation. An implication of this diverse experimental approach is that phylogenetically divergent organisms employ uniquely adapted mechanisms of cell volume regulation. Given the probability that changes in extracellular osmolality were physiological stresses faced by the earliest organisms, it is more likely that cell volume regulation proceeds by highly conserved physiological processes. We review volume regulation from a comparative perspective, drawing examples from all five taxonomic kingdoms. Specifically, we discuss the role of inorganic and organic solutes in volume maintenance and the mechanisms by which the concentrations of these osmolytes are regulated. In addition, the processes that may transduce volume perturbations into regulatory responses, such as stretch activation of ion channels, intracellular signaling, and genomic regulation, are discussed. Throughout this review we emphasize areas we feel are important for future research.
从五个生物分类界中选取的各种生物体和细胞类型，无论是自然地还是通过实验手段，都会受到渗透胁迫。对这些挑战的一种常见生理反应是通过改变细胞内无机和有机溶质（统称为渗透溶质）的浓度来维持细胞体积。关于这些溶质浓度调节机制的研究沿着几条实验路线进行。在脊椎动物细胞和组织中对渗透激活的离子转运途径进行了广泛研究。我们对有机渗透溶质的许多了解来自对无脊椎动物、细菌和原生生物的研究。细菌遗传学的相对简单性为探索体积调节过程中基因表达的变化提供了一个强大而精妙的工具。这种多样的实验方法意味着，在系统发育上不同的生物体采用独特适应的细胞体积调节机制。鉴于细胞外渗透压变化可能是最早的生物体面临的生理压力，细胞体积调节更有可能通过高度保守的生理过程进行。我们从比较的角度回顾体积调节，从所有五个生物分类界中举例说明。具体而言，我们讨论无机和有机溶质在维持体积中的作用以及这些渗透溶质浓度的调节机制。此外，还讨论了可能将体积扰动转化为调节反应的过程，如离子通道的拉伸激活、细胞内信号传导和基因组调节。在这篇综述中，我们强调了我们认为对未来研究很重要的领域。
