title: Acid secretion by mitochondrion-rich cells of medaka (Oryzias latipes) acclimated to acidic freshwater.
abstract: In the present study, medaka embryos were exposed to acidified freshwater (pH 5) to investigate the mechanism of acid secretion by mitochondrion-rich (MR) cells in embryonic skin. With double or triple in situ hybridization/immunocytochemistry, the Na(+)/H(+) exchanger 3 (NHE3) and H(+)-ATPase were localized in two distinct subtypes of MR cells. NHE3 was expressed in apical membranes of a major proportion of MR cells, whereas H(+)-ATPase was expressed in basolateral membranes of a much smaller proportion of MR cells. Gill mRNA levels of NHE3 and H(+)-ATPase and the two subtypes of MR cells in yolk sac skin were increased by acid acclimation; however, the mRNA level of NHE3 was remarkably higher than that of H(+)-ATPase. A scanning ion-selective electrode technique was used to measure H(+), Na(+), and NH(4)(+) transport by individual MR cells in larval skin. Results showed that Na(+) uptake and NH(4)(+) excretion by MR cells increased after acid acclimation. These findings suggested that the NHE3/Rh glycoprotein-mediated Na(+) uptake/NH(4)(+) excretion mechanism plays a critical role in acidic equivalent (H(+)/NH(4)(+)) excretion by MR cells of the freshwater medaka.
authors: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, ROC.
authors: Chia-Cheng
authors: CC
authors: Lin
authors: Li-Yih
authors: LY
authors: Lin
authors: Hao-Hsuan
authors: HH
authors: Hsu
authors: Violette
authors: V
authors: Thermes
authors: Patrick
authors: P
authors: Prunet
authors: Jiun-Lin
authors: JL
authors: Horng
authors: Pung-Pung
authors: PP
authors: Hwang
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D005618:Fresh Water / Q000737:chemistry*; D005880:Gills / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D009990:Oryzias / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D012867:Skin / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism
chemical_list: D017923:Sodium-Hydrogen Exchangers; D006180:Proton-Translocating ATPases