Rosenstiel School of Marine & Atmospheric Science, Department of Marine Biology & Fisheries, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2011 Jun;159(2):150-8. doi: 10.1016/j.cbpa.2011.02.011. Epub 2011 Feb 22.
The ability to transition from freshwater to seawater environments is an intrinsic requirement of the life history of some fish species, including the anadromous rainbow trout (Oncorhynchus mykiss). The differences between hyper- and hypoosmoregulation are developed quickly (in hours to days), and at all scales, from gene expression to organ function. In this study, intestinal ion and water transport was examined in O. mykiss following acute transfer from freshwater (FW) to 70% seawater (SW). Plasma [Mg²+] increased at 24h post-transfer but recovered by 72 h. In the intestinal fluids, total CO₂ was found to increase with SW exposure/acclimation, while [Na+] decreased after 24h of SW exposure. Overall, in vitro experiments demonstrated the importance of base secretion to epithelial water uptake, and suggested that the primary physiological adjustments occurred 24-72 h after acute SW transfer. The mRNA expression of ion transporters important for intestinal osmoregulation and maintenance of acid-base balance was also investigated. A Na+/H+ exchanger (NHE2) and anion exchanger (SLC26a6) were hypothesized to be involved in the transport of acid-base equivalents, Na+, and Cl⁻, but were not uniformly expressed across tissue samples, and expression, where present, did not change following salinity transfer. NHE1, however, was expressed in all examined tissues (gill, kidney, anterior intestine, and pyloric cecae), but exhibited no changes in expression following acute salinity transfer.
从淡水环境到海水环境的转变能力是一些鱼类物种生命周期的内在要求，包括溯河洄游的虹鳟鱼（Oncorhynchus mykiss）。高渗和低渗调节的差异在所有尺度上都很快发展，从基因表达到器官功能。在这项研究中，虹鳟鱼在急性从淡水（FW）转移到 70%海水（SW）后，研究了其肠道离子和水的转运。在转移后 24 小时，血浆[Mg²⁺]增加，但在 72 小时内恢复。在肠道液中，随着海水暴露/适应，总 CO₂被发现增加，而[Na⁺]在暴露于海水 24 小时后减少。总的来说，体外实验表明基底分泌对上皮细胞水吸收的重要性，并表明主要的生理调整发生在急性 SW 转移后 24-72 小时。还研究了对肠道渗透压调节和酸碱平衡维持很重要的离子转运体的 mRNA 表达。Na+/H+交换器（NHE2）和阴离子交换器（SLC26a6）被假设参与酸碱当量、Na+和 Cl⁻的转运，但在组织样本中并非均匀表达，并且在盐度转移后表达没有变化。然而，NHE1 在所有检查的组织（鳃、肾脏、前肠和幽门盲囊）中都有表达，但在急性盐度转移后表达没有变化。
