Department of Pharmacology and Toxicology, University of Lausanne, 1005 Lausanne, Switzerland.
Mol Cell Endocrinol. 2012 Feb 5;349(1):51-5. doi: 10.1016/j.mce.2011.06.037. Epub 2011 Jul 8.
Many basic physiological functions exhibit circadian rhythmicity. These functional rhythms are driven, in part, by the circadian clock, an ubiquitous molecular mechanism allowing cells and tissues to anticipate regular environmental events and to prepare for them. This mechanism has been shown to play a particularly important role in maintaining stability (homeostasis) of internal conditions. Because the homeostatic equilibrium is continuously challenged by environmental changes, the role of the circadian clock is thought to consist in the anticipative adjustment of homeostatic pathways in relation with the 24h environmental cycle. The kidney is the principal organ responsible for the regulation of the composition and volume of extracellular fluids (ECF). Several major parameters of kidney function, including renal plasma flow (RPF), glomerular filtration rate (GFR) and tubular reabsorption and secretion have been shown to exhibit strong circadian oscillations. Recent evidence suggest that the circadian clock can be involved in generation of these rhythms through external circadian time cues (e.g. humoral factors, activity and body temperature rhythms) or, trough the intrinsic renal circadian clock. Here, we discuss the role of renal circadian mechanisms in maintaining homeostasis of water and three major ions, namely, Na(+), K(+) and Cl(-).
许多基本的生理功能都表现出昼夜节律性。这些功能节律部分是由生物钟驱动的，生物钟是一种普遍存在的分子机制，允许细胞和组织预测规律的环境事件并为其做准备。该机制已被证明在维持内部条件的稳定性（稳态）方面发挥着特别重要的作用。由于内环境平衡不断受到环境变化的挑战，人们认为生物钟的作用在于根据 24 小时的环境周期，对稳态途径进行预期性的调节。肾脏是调节细胞外液（ECF）组成和容量的主要器官。肾脏功能的几个主要参数，包括肾血浆流量（RPF）、肾小球滤过率（GFR）和肾小管重吸收和分泌，已被证明具有很强的昼夜节律性波动。最近的证据表明，生物钟可以通过外部的昼夜时间线索（例如，体液因素、活动和体温节律）或通过内在的肾脏生物钟来参与这些节律的产生。在这里，我们讨论了肾脏昼夜节律机制在维持水和三种主要离子（即 Na(+)、K(+) 和 Cl(-)）稳态方面的作用。
