Vitamin D regulates transepithelial acid secretion in zebrafish (Danio rerio) larvae

Maintenance of an acid-base balance is essential for normal physiological processes in vertebrates. Freshwater fishes live aquatic environment with variable pH, and their buffering capacity body fluids weak. Thus, after acid exposure, secrete excess to prevent internal acidosis. Acid-secreting ionocytes present the adult gills embryonic skin are primarily responsible secretion, H + -ATPase Na /H exchanger 3 (NHE3) two main transporters apical secretion. Vitamin D a well-known hormone involved maintenance Ca 2+ homeostasis suggested be regulation by modulating activity and/or mRNA expression NHE3 mammalian models. It remains unclear whether vitamin secretion fishes. The aim study was use zebrafish as model determine its receptors influence Our results indicated that levels 1?, 25-dihydroxyvitamin (1?,25(OH) 2 ), bioactive D, were significantly increased days post-fertilization larvae exposure acidic freshwater (AFW, pH 4.0). Exogenous 1?,25(OH) (20 ?g/L) incubation substantially enhanced acid-secreting at entire each -ATPase-rich cell (HRC), type ionocyte. Furthermore, (VDRs) identified HRCs zebrafish. When both VDRa VDRb knocked down, decreased. Moreover, double knockdown VDRa/b prevented increase induced AFW treatment. This first indicate fish.