Copper induced alterations of biochemical parameters in the gill and plasma of Oreochromis niloticus.
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.
Monteiro
Sandra M
SM
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
Mancera
Juan M
JM
Fontaínhas-Fernandes
António
A
Sousa
Mário
M
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
D001798:Blood Proteins; D002712:Chlorides; D003300:Copper; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D006854:Hydrocortisone