Effects of water-borne copper on branchial chloride cells and Na+/K+-ATPase activities in Mozambique tilapia (Oreochromis mossambicus)

Autor: E.S. Quabius, Gert Flik, S.E. Wendelaar Bonga, J. Li, R.A.C. Lock
Jazyk: angličtina
Rok vydání: 1998
Předmět:
Zdroj: Aquatic Toxicology, 43, 1-11. Elsevier science bv
Aquatic Toxicology, 43, 1, pp. 1-11
ISSN: 0166-445X
Popis: Freshwater tilapia (Oreochromis mossambicus) were exposed for different periods up to 28 days to 3.2 μM of water-borne Cu. Electron microscopical analysis of the gills demonstrated significant changes in the structure and number of chloride cells (CCs) from Cu-exposed fish when compared to controls. These cells, which are the main location of the Na+/K+-ATPase of the gills and which play a crucial role in transepithlial Na+ transport, showed a time-related increase of degeneration by apoptosis and necrosis in the Cu-exposed fish. After 28 days of Cu exposure, apoptotic CCs had doubled in number while necrotic CCs had even increased by a factor of ten. The activity of the gill Na+/K+-ATPase and the plasma Na+ concentration decreased in time and in parallel. An inverse relationship between the Na+/K+-ATPase specific activity and the branchial Cu content further supports the notion that this enzyme is very sensitive to Cu2+ inhibition. In contrast to controls, no significant correlation was found in the Cu-exposed fish between the opercular CC number and the gill Na+/K+-ATPase total activities, despite the large increase in number of these cells. This study provides further evidence that not only the number but also the quality of the CCs, may determine to a large extent the branchial capacity of a freshwater fish to absorb Na+ from the surrounding water.
Databáze: OpenAIRE
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