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 NH4 + transport by individual MR cells in larval skin. Results showed that Na + uptake and NH4 + excretion by MR cells increased after acid acclimation. These findings suggested that the NHE3/Rh glycoprotein-mediated Na + uptake/NH4 + excretion mechanism plays a critical role in acidic equivalent (H +/NH4 +) excretion by MR cells of the freshwater medaka.
|期刊||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|出版狀態||已發佈 - 一月 2012|
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