EFFECTS OF CADMIUM AND BENZO(A)PYRENE ON THE IMMUNE-SYSTEM, GILL ATPASE AND EROD ACTIVITY OF EUROPEAN SEA BASS DICENTRARCHUS-LABRAX

Juvenile European sea bass (Dicentrarchus labrax) were exposed to cadm ium (40 mu g 1(-1)) for 15 days and then injected with benzo(a)pyrene (BaP) (20 mg kg(-1)) for 14 h. In the immune system, phagocytosis was reduced both in spleen and kidney macrophages after cadmium-exposure a nd/or BaP injection, with a synergistic effect of the combined polluta nts. Spleen and kidney respiratory burst (measured by hydrogen peroxid e production) showed different patterns of response to cadmium and BaP . Cadmium exposure had no effect on spleen macrophages, although BaP t otally inhibited the respiratory burst. In kidney macrophages, cadmium -exposure and BaP injection resulted in enhanced hydrogen peroxide pro duction. After BaP injection, hepatic micrososomal 7-ethoxyresorufin-O -deethylase (EROD) activity was increased 21-fold compared with the co ntrol, but the induction was even greater (34.5 times compared with th e control) in cadmium-exposed fish. However, although an induction (11 times compared to the control) occurred after cadmium exposure the ef fects of both pollutants were not synergistic (not additional). No per turbation of the gill Na+/K+-ATPase activity was observed in cadmium-e xposed fish, but the activity was increased in BaP-injected fish. The role of BaP metabolites and cadmium as both direct effecters and indir ect stressors, responsible for the changes in the immune system and gi ll and liver biochemistry of the fish are discussed.