A histological study of the kidney structure of Van fish (<i>Alburnus tarichi</i>) acclimated to highly alkaline water and freshwater

Abstract

Kidneys are important organs that play a role in ion and water regulation in different aquatic environments. The Van fish (Alburnus tarichi, Güldenstädt, 1814) has acclimated to the alkaline waters of the largest saline soda lake in the world. In this study, changes in kidney tissue were examined histologically in alkaline and freshwater as the fish entered freshwater for reproduction. In addition, immunological changes were examined for Na+, K+, ATPase (NKA), an important transmembrane protein in kidneys. A histological comparison of the kidneys of fish taken from both environments was made. The glomerular volume was larger in fish acclimated to freshwater, and the collecting tubules were larger in diameter and had thicker walls. The fish acclimated to alkaline lake water had reduced numbers of glomeruli of smaller size. NKA enzyme was present in tubules within kidneys in both environments. It was, however, observed more frequently in fish acclimated to freshwater. Although plasma osmolality and Cl− values decreased in the fish acclimated to freshwater, hematocrit values increased (p < 0.05). No changes were observed in the muscle water content between alkaline water- and freshwater-acclimated fish. We clearly demonstrate that histologic and immunochemical changes take place in the kidney of the Van fish acclimated to the different physicochemical characteristics of alkaline and freshwater environments.