Mechanism of acid adaptation of a fish living in a pH 3.5 lake

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2003-05, Vol.284 (5), p.1199-R1212
• Main Authors: Hirata, Taku, Kaneko, Toyoji, Ono, Toshihiro, Nakazato, Takeru, Furukawa, Norihisa, Hasegawa, Sanae, Wakabayashi, Shigeo, Shigekawa, Munekazu, Chang, Min-Hwang, Romero, Michael F, Hirose, Shigehisa
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Animals; Aquaporin 3; Aquaporins - metabolism; Carbonic Anhydrase II - genetics; Cloning, Molecular; Enzyme Induction; Fishes - physiology; Fresh Water - chemistry; Gills - enzymology; Hydrogen-Ion Concentration; Japan; Kidney - enzymology; Oocytes; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sodium - metabolism; Sodium-Bicarbonate Symporters - genetics; Sodium-Bicarbonate Symporters - metabolism; Sodium-Hydrogen Exchangers - genetics; Sodium-Hydrogen Exchangers - metabolism; Sodium-Potassium-Exchanging ATPase - genetics; Up-Regulation; Xenopus laevis
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00267.2002

1  Department of Biological Sciences, Tokyo Institute of Technology, Yokohama 226-8501; 2  Ocean Research Institute, University of Tokyo, Tokyo 164-8639; 3  Department of Molecular Physiology, National Cardiovascular Center Research Institute, Osaka 565-8565, Japan; and 4  Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106 Despite unfavorable conditions, a single species of fish, Osorezan dace, lives in an extremely acidic lake (pH 3.5) in Osorezan, Aomori, Japan. Physiological studies have established that this fish is able to prevent acidification of its plasma and loss of Na + . Here we show that these abilities are mainly attributable to the chloride cells of the gill, which are arranged in a follicular structure and contain high concentrations of Na + -K + -ATPase, carbonic anhydrase II, type 3 Na + /H + exchanger (NHE3), type 1 Na + -HCO cotransporter, and aquaporin-3, all of which are upregulated on acidification. Immunohistochemistry established their chloride cell localization, with NHE3 at the apical surface and the others localized to the basolateral membrane. These results suggest a mechanism by which Osorezan dace adapts to its acidic environment. Most likely, NHE3 on the apical side excretes H + in exchange for Na + , whereas the electrogenic type 1 Na + -HCO cotransporter in the basolateral membrane provides HCO for neutralization of plasma using the driving force generated by Na + -K + -ATPase and carbonic anhydrase II. Increased expression of glutamate dehydrogenase was also observed in various tissues of acid-adapted dace, suggesting a significant role of ammonia and bicarbonate generated by glutamine catabolism. aquaporin; carbonic anhydrase; glutamine catabolism; sodium-bicarbonate cotransporter; sodium/proton exchanger