Hu Marian Y, Sung Po-Hsuan, Guh Ying-Jey, Lee Jay-Ron, Hwang Pung-Pung, Weihrauch Dirk, Tseng Yung-Che
Institute of Physiology, University of KielKiel, Germany; Institute of Cellular and Organismic Biology, Academia SinicaTaipei, Taiwan.
Department of Life Science, National Taiwan University Taipei, Taiwan.
Front Physiol. 2017 Mar 20;8:162. doi: 10.3389/fphys.2017.00162. eCollection 2017.
In contrast to terrestrial animals most aquatic species can be characterized by relatively higher blood [Formula: see text] concentrations despite its potential toxicity to the central nervous system. Although many aquatic species excrete [Formula: see text] via specialized epithelia little information is available regarding the mechanistic basis for NH/[Formula: see text] homeostasis in molluscs. Using perfused gills of we studied acid-base regulation and ammonia excretion pathways in this cephalopod species. The octopus gill is capable of regulating ammonia (NH/[Formula: see text]) homeostasis by the accumulation of ammonia at low blood levels (<260 μM) and secretion at blood ammonia concentrations exceeding levels of 300 μM. [Formula: see text] transport is sensitive to the adenylyl cyclase inhibitor KH7 indicating that this process is mediated through cAMP-dependent pathways. The perfused octopus gill has substantial pH regulatory abilities during an acidosis, accompanied by an increased secretion of [Formula: see text]. Immunohistochemical and qPCR analyses revealed tissue specific expression and localization of Na/K-ATPase, V-type H-ATPase, Na/H-exchanger 3, and Rhesus protein in the gill. Using the octopus gill as a molluscan model, our results highlight the coupling of acid-base regulation and nitrogen excretion, which may represent a conserved pH regulatory mechanism across many marine taxa.
与陆生动物不同，大多数水生生物的特点是血液中[公式：见正文]浓度相对较高，尽管其对中枢神经系统具有潜在毒性。尽管许多水生生物通过特化上皮细胞排泄[公式：见正文]，但关于软体动物中NH/[公式：见正文]稳态的机制基础的信息却很少。我们利用[物种名称]的灌流鳃，研究了这种头足类动物的酸碱调节和氨排泄途径。章鱼鳃能够通过在低血氨水平（<260μM）时积累氨以及在血氨浓度超过300μM时分泌氨来调节氨（NH/[公式：见正文]）稳态。[公式：见正文]转运对腺苷酸环化酶抑制剂KH7敏感，表明该过程是通过cAMP依赖性途径介导的。在酸中毒期间，灌流的章鱼鳃具有显著的pH调节能力，同时伴随着[公式：见正文]分泌增加。免疫组织化学和qPCR分析揭示了鳃中Na/K - ATP酶、V型H - ATP酶、Na/H交换体3和恒河猴蛋白的组织特异性表达和定位。以章鱼鳃作为软体动物模型，我们的结果突出了酸碱调节与氮排泄的耦合，这可能代表了许多海洋类群中一种保守的pH调节机制。
