Immunological detection of Na(+)/H(+) exchangers in the gills of a hagfish, Myxine glutinosa, an elasmobranch, Raja erinacea, and a teleost, Fundulus heteroclitus.

Na(+)/H(+) exchangers (NHE) are a family of ion exchangers with diverse functions that are well defined in mammals. NHE-1 is expressed in the plasma membrane of most mammalian cells where it regulates intracellular pH, and usually in the basolateral membrane of epithelial cells. It has also been detected in teleost gills where it may participate in systemic pH regulation. NHE-3 is usually expressed in the apical membrane of mammalian epithelial cells where it helps reabsorb Na(+) and HCO(3)(-); it has also been detected in teleost gills. We used Western blotting and heterologous antibodies to screen for expression of NHE-1 and NHE-3 in gills of an agnathan (Myxine glutinosa) and an elasmobranch (Raja erinacea), and NHE-3 in gills of a teleost (Fundulus heteroclitus). Positive NHE-1 bands were detected in gills from the agnathan and elasmobranch. Using the NHE-3 antibody, bands were detected in the gills of the elasmobranch and teleost. These data are some of the first direct evidence of NHEs in the gills of an agnathan and elasmobranch, and confirm the presence of NHEs in the gills of teleosts.