Immunolocalisation of NHE3-like immunoreactivity in the gills of the rainbow trout (Oncorhynchus mykiss) and the blue-throated wrasse (Pseudolabrus tetrious)

Na+/H+ exchange has been implicated in models of ion transport across the b ranchial epithelium of marine and freshwater fishes. In this preliminary st udy, we present immunohistochemical data using a polyclonal antibody raised against NHE3 which show NHE3-like immunoreactivity (IR) in the gills from a freshwater and a marine teleost species. In both species, branchial epith elial cells demonstrating NHE3-like IR were localised predominantly to the junction between the filament and the secondary lamellae. However, there wa s a marked difference in the morphology of the NHE3-like immunoreactive epi thelial cells between the species. This morphological difference between th e species suggests functional differences in the exchanger, which may be re lated to marine versus freshwater environments.