Kaasik Allen, Safiulina Dzhamilja, Zharkovsky Alexander, Veksler Vladimir
Department of Pharmacology, Centre of Molecular and Clinical Medicine, University of Tartu, Ravila 19, 51014 Tartu, Estonia.
Am J Physiol Cell Physiol. 2007 Jan;292(1):C157-63. doi: 10.1152/ajpcell.00272.2006. Epub 2006 Jul 26.
Mitochondrial volume homeostasis is a housekeeping cellular function essential for maintaining the structural integrity of the organelle. Changes in mitochondrial volume have been associated with a wide range of important biological functions and pathologies. Mitochondrial matrix volume is controlled by osmotic balance between cytosol and mitochondria. Any dysbalance in the fluxes of the main intracellular ion, potassium, will thus affect the osmotic balance between cytosol and the matrix and promote the water movement between these two compartments. It has been hypothesized that activity of potassium efflux pathways exceeds the potassium influx in functioning mitochondria and that potassium concentration in matrix could be actually lower than in cytoplasm. This hypothesis provides a clear-cut explanation for the mitochondrial swelling observed after mitochondrial depolarization, mitochondrial calcium overload, or opening of permeability transition pore. It should also be noted that the rate of water flux into or out of the mitochondrion is determined not only by the osmotic gradient that acts as the driving force for water transport but also by the water permeability of the inner membrane. Recent data suggest that the mitochondrial inner membrane has also specific water channels, aquaporins, which facilitate water movement between cytoplasm and matrix. This review discusses different phases of mitochondrial swelling and summarizes the potential effects of mitochondrial swelling on cell function.
线粒体体积稳态是一种维持细胞器结构完整性所必需的细胞管家功能。线粒体体积的变化与多种重要的生物学功能和病理状态相关。线粒体基质体积由细胞质和线粒体之间的渗透平衡控制。因此，主要细胞内离子钾的通量失衡会影响细胞质和基质之间的渗透平衡，并促进这两个区室之间的水移动。据推测，在功能正常的线粒体中钾外流途径的活性超过钾内流，并且基质中的钾浓度实际上可能低于细胞质中的钾浓度。这一假设为线粒体去极化、线粒体钙超载或通透性转换孔开放后观察到的线粒体肿胀提供了明确的解释。还应注意的是，水进出线粒体的速率不仅取决于作为水运输驱动力的渗透梯度，还取决于内膜的水通透性。最近的数据表明，线粒体内膜也有特定的水通道——水孔蛋白，其促进细胞质和基质之间的水移动。本综述讨论了线粒体肿胀的不同阶段，并总结了线粒体肿胀对细胞功能的潜在影响。
