PIERMARINI, P.M.*; VERLANDER-REED, J.V.; ROYAUX, I.E.; EVANS, D.H.: Immunochemical Evidence for Pendrin in the Gills of the Euryhaline Atlantic Stingray (Dasyatis sabina): Implications for Ionic and Acid/Base Regulation
Pendrin is recognized as an important Cl–/HCO3– exchanger in the mammalian kidney. This transporter has been localized in the apical membrane of B-type intercalated cells, which are characterized by a basolateral membrane localization of the vacuolar-proton-ATPase (V-H-ATPase). Pendrin has not been investigated in lower vertebrates. In fresh and seawater fishes, gills are the main site of Cl–/HCO3– exchange, but the molecular identity of the exchanger is uncertain. In this study, we used immunochemical techniques to determine if pendrin was present in gills of an elasmobranch fish, the Atlantic stingray (Dasyatis sabina). A heterologous antibody to pendrin cross-reacted with a peptide of approximately 130 kDa in the gills of fresh and seawater stingrays. Expression of the peptide was highest in gills of freshwater stingrays. Double-label immunohistochemistry of the gill epithelium revealed that pendrin was localized in the apical membrane of intercalated cells with basolateral V-H-ATPase, suggesting that the V-H-ATPase-cells have a similar function to B-type intercalated cells of the mammalian kidney (Cl–/HCO3– exchange). The higher expression of pendrin in freshwater stingray gills implies that the exchanger plays an important role in Cl– uptake and HCO3– excretion in freshwater environments. Supported by EPA STAR Grant U-915419-01-0 (PMP) and NSF Grant IBN-9604824 (DHE).
