A review on the activity of Na+/K+-ATPase in branchial ionocytes and its role in salinity adaptation among diadromous species

Freshwater and saltwater environments have opposite osmotic gradients. In freshwater, organisms tend to uptake ions from the surrounding, while in saltwater, they need to excrete the excess ions. Branchial ionocytes play a significant role in euryhaline teleost species that migrate to different salinity gradients as part of their life cycle. Ionocytes are highly dependent on the activity of Na+/K+-ATPase (NKA) in salinity adaptation. Thus, this review article determines the factors affecting NKA activity in ionocytes and its role in salinity adaptation among diadromous species. Several findings suggest that NKA activity is affected by various factors such as hormones, nutrition, and gene expression. Ionocytes enriched with NKA have many functions in diadromous depending on their types, location, size, and number in branchial necessary for these organisms to carry out their biological function in ionic-regulatory processes.