The effect of Cu on gill and esophagus lipid metabolism in the rainbow trout Oncorhynchus mykiss

Rainbow trout Oncorhynchus mykiss were exposed to 0, 100, 300 and 800 μgl⁻¹ ambient Cu in brackish water (BW) for 4 days at 13 °C and subsequently transferred to either clean BW, clean fresh water (FW) or clean seawater (SW) at 16 °C. After incubation with ³²P-phosphate and ¹⁴C-acetate added as precursors to the water the fish showed a degradation, depending on previous [CU], of ³²P- and ¹⁴C-labelled gill membrane phospholipids if they had been transferred to SW or remained in BW. Corresponding experiments where the fish were exposed to Cu in BW for 12 days showed a similar subsequent degradation in SW and BW of both gill and esophagus membrane phospholipids, however to a much lesser degree in gill tissue than after 4 days. Plasma Na⁺ was similarly reduced by up to 8%, depending on previous ambient Cu, but in this case only after transfer to FW and only after 4 days of exposure. Both the effect on membrane lipid metabolism and plasma Na⁺ thus showed acclimation to ambient Cu but there was apparently no direct correlation between the two different types of observed changes in membrane function.