Figure 12.

Role of NCBTs in the gills and intestines of bony fishes. In the gill epithelia of freshwater fish such as trout (A), NBCe1 contributes to Na⁺ and HCO₃⁻ absorption from the water. In the gut epithelia of marine fishes such as pufferfish (B), NBCe1 contributes to HCO₃⁻ secretion into the gut lumen. ENaC is an epithelial Na⁺ channel. The identities of the non-Slc4 transporters involved in these pathways have not been determined for all species in which these systems have been identified.