Environmental cadmium exposure and metabolic responses of the Nile tilapia, Oreochromis niloticus

The contamination of water by metal compounds is a worldwide environmental problem. This study was undertaken to evaluate the impact of short-term cad mium exposure on metabolic patterns of the freshwater fish Oreochromis nilo ticus. The fish were exposed to 320, 640, 1280 and 2560 mug/l sublethal con centrations of Cd++ (CdCl2) in water for 7 days. The specific activities of the enzymes phosphofructo kinase (PFK-E.C.2.7.1.11.), lactate dehydrogenas e (LDH-E.C.1.1.1.27.) and creatine kinase (CK-E.C.2.7.3.2.) were decreased in white muscle after cadmium treatments, indicating decreases in the capac ity of glycolysis in this tissue. Cadmium exposure induced increased glucos e concentration in white muscle of fish. On the other hand, cadmium exposur e at sublethal concentrations increased phosphofructo kinase and LDH in red muscle of fish. Cadmium significantly decreased total protein concentratio ns in liver and white muscle regardless of tissue glycogen levels. The data suggest that cadmium acts as a stressor, leading to metabolic alterations similar to those observed in starvation. (C) 2001 Elsevier Science Ltd. All rights reserved.