Front Horm Res. 2019;52:8-23. doi: 10.1159/000493233. Epub 2019 Jan 15.
In the evolutionary process, the successful adaptation of living organisms initially to an aqueous and thereafter to an arid terrestrial environment posed radically different challenges to the maintenance of water balance. Whereas the former required defense against water excess, the latter called for water conservation. To meet such challenges, the mammalian nephron evolved mechanisms for increasing both water excretion by diluting and water conservation by concentrating the urine. This chapter reviews the process whereby the osmosensors control thirst and the secretion of the antidiuretic hormone (vasopressin) to allow for either urinary dilution or concentration and thereby delicately maintain tonicity of body fluids within a very narrow range. Central to this process is the now well-defined cellular pathway whereby vasopressin renders the collecting duct, water permeable. Disorders of vasopressin secretion and action result in disturbances of body fluids tonicity, which are clinically recognized as abnormalities in reduced plasma sodium concentration or hyponatremia.
在进化过程中，生物最初成功适应水生环境，而后又适应干旱陆地环境，这对水盐平衡的维持带来了截然不同的挑战。前者需要防止水分过多，而后者则需要节约用水。为了应对这些挑战，哺乳动物肾单位进化出了通过稀释来增加尿液排泄和通过浓缩来保存水分的机制。本章回顾了渗透压感受器控制口渴和抗利尿激素（血管加压素）分泌的过程，以允许尿液稀释或浓缩，从而在非常狭窄的范围内精细地维持体液渗透压。这一过程的核心是现在已经明确的细胞途径，即血管加压素使集合管具有水通透性。血管加压素分泌和作用的紊乱会导致体液渗透压紊乱，临床上表现为血浆钠浓度降低或低钠血症的异常。
