title: Copper induced alterations of biochemical parameters in the gill and plasma of Oreochromis niloticus.
abstract: The main objective of this study was to determine the effects of copper exposure on copper accumulated in branchial tissue, gill Na+/K+-ATPase activity and plasma Na+, Cl-, osmolality, protein, glucose and cortisol, in Oreochromis niloticus. Fish were experimentally exposed to 40 and 400 microg L(-1) of waterborne copper and sacrified after 0, 3, 7, 14 and 21 days. Copper accumulation and Na+/K+-ATPase activity were determined in branchial tissue, whereas osmolality, Na+, Cl-, protein, glucose and cortisol concentrations were measured in plasma samples. Gill copper accumulation increased linearly with exposure time and concentration, whereas gill Na+/K+-ATPase activity was maximally inhibited after 3 days of exposure and showed a significant negative correlation with copper tissue levels. Plasma Cl- values decreased with time of exposure but only at 400 microg L(-1) of copper. Plasma Na+, protein and osmolality decreased with exposure time at the highest copper concentration tested, whereas at 40 microg L(-1) of copper this effect was only observed after 21 days of exposure. Plasma glucose and cortisol levels increased in a dose and time dependent manner, while showing complex fluctuations during the intermediate exposure times. In conclusion, copper induces an early maximum inhibition of gill Na+/K+-ATPase activity in O. niloticus. The subsequent slow decrease in ion plasma levels was related to compensatory mechanisms involving a non-specific stress response that appeared overcome at long-term exposures.
authors.affiliation: University of Trás-os-Montes and Alto Douro (UTAD) and Center for Technological Studies of Environmental and Life Sciences (CETAV), Vila Real, Portugal. smonteir@utad.pt
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Monteiro
authors.forename: Juan M
authors.initials: JM
authors.lastname: Mancera
authors.forename: António
authors.initials: A
authors.lastname: Fontaínhas-Fernandes
authors.forename: Mário
authors.initials: M
authors.lastname: Sousa
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000032:analysis; D002712:Chlorides / Q000097:blood; D023681:Cichlids / Q000378:metabolism*; D003300:Copper / Q000378:metabolism / Q000633:toxicity*; D005880:Gills / Q000187:drug effects* / Q000378:metabolism; D006854:Hydrocortisone / Q000097:blood; D009994:Osmolar Concentration; D012964:Sodium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D001798:Blood Proteins; D002712:Chlorides; D003300:Copper; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D006854:Hydrocortisone