Perfused Gills Reveal Fundamental Principles of pH Regulation and Ammonia Homeostasis in the Cephalopod Octopus vulgaris.

Hu, Marian Yong-An, Sung, P.-H., Guh, Y.-J., Lee, J.-R., Hwang, P.-P., Weihrauch, D. and Tseng, Y.-C. (2017) Perfused Gills Reveal Fundamental Principles of pH Regulation and Ammonia Homeostasis in the Cephalopod Octopus vulgaris. Open Access Frontiers in Physiology, 8 . DOI 10.3389/fphys.2017.00162.

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Abstract

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 NH3/[Formula: see text] homeostasis in molluscs. Using perfused gills of Octopus vulgaris we studied acid-base regulation and ammonia excretion pathways in this cephalopod species. The octopus gill is capable of regulating ammonia (NH3/[Formula: see text]) homeostasis by the accumulation of ammonia at low blood levels (<260 μM) and secretion at blood ammonia concentrations exceeding in vivo 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.

Document Type: Article
Keywords: NH3/NH4+ homeostasis; Na+/K+-ATPase; Rh-protein; acid-base regulation; cephalopod; invertebrate
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
Kiel University
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.3389/fphys.2017.00162
ISSN: 1664-042X
Projects: Future Ocean
Date Deposited: 17 Oct 2017 11:41
Last Modified: 13 Dec 2017 10:58
URI: http://oceanrep.geomar.de/id/eprint/39932

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