A hypothesis on the involvement of high-density lipoproteins (HDL) in maintaining osmotic homeostasis in fish was proposed. For its verification, structural reorganizations of serum HDL in the goldfish Carassius auratus L. were investigated under natural conditions (during the seasonal dynamics) and in experiments on the effect of critical salinity. A common algorithm of HDL rearrangements in wild freshwater fish and those acclimated experimentally to critical salinity was established. It consists in reversible dissociation–association of HDL particles. In the natural (freshwater) habitat, this algorithm is congruent with the dynamics of total protein distribution across the capillary wall, while under experimental conditions with changes in water salinity. These findings imply the possibility of multiple strategies of maintaining osmotic homeostasis with the involvement of HDL in higher teleosts the blood of which, in contrast to mammals, lacks a specialized osmotically active protein albumin. The role of HDL as universal metabolic regulators and stabilizers is discussed.

中文翻译：

---

高密度脂蛋白在维持金鱼 Carassius auratus L.（鲤科）渗透稳态中的作用

提出了关于高密度脂蛋白 (HDL) 参与维持鱼体内渗透压稳态的假设。为了验证，研究了金鱼 Carassius auratus L. 血清 HDL 的结构重组在自然条件下（在季节性动态期间）和临界盐度影响的实验。建立了野生淡水鱼和那些通过实验适应临界盐度的 HDL 重排的通用算法。它包括HDL颗粒的可逆解离-缔合。在自然（淡水）栖息地中，该算法与整个毛细管壁的总蛋白质分布动态一致，而在水盐度变化的实验条件下。这些发现暗示了通过 HDL 参与维持渗透稳态的多种策略的可能性，这些硬骨鱼的血液与哺乳动物相比，缺乏专门的渗透活性蛋白白蛋白。讨论了 HDL 作为通用代谢调节剂和稳定剂的作用。