Alterations in enzymes in an Indian catfish, Clarias batrachus (Linn.), exposed to vanadium.

Abstract

The increase in air and water borne concentrations of vanadium, a physiologically and pharmacologically active substance, has caused renewed interest in the toxicology of this metal. Toxicity studies of vanadium on fish are comparatively scarce. Cytochrome P-450 monoxygenases and conjugating enzymes are important in fish metabolism and elimination of endogenous as well as foreign lipophilic compounds. These enzymes are also known to participate in activation and inactivation of carcinogenic and environmental chemicals. (In vitro) investigations have shown that fish metabolize xenobiotics by mechanisms very similar to those found in mammals. Impairment of drug-metabolizing enzymes is thus deleterious to the organism. Heavy metals are known to influence this group of enzymes. This prompted us to investigate the effect of vanadate, in a dose-responsive and time-dependent manner, on the relative rates and patterns of hepatic glutathione transferase (GST) activity, UDP-glucuronyl transferase (UDPGT) activity and cytochrome P-450 (Cyt P-450) level in an Indian catfish, Clarias batrachus. We chose an aquatic species for our experiment since the environment where aquatic animals live is the main destination of industrial and agricultural wastes. The variations recorded in the level and activity of cytochrome P-450, glutathione transferase and UDP-glu-curonyl transferase are discussed in relation to carcinogenic riskmore » depending on the environment of the fish. In support of the above, petroleum has been found to induce cytochrome P-450 and subsequently produce high levels of neoplasia in fish. Furthermore, GST, UDPGT and Cyt P-450 have been reported as reliable markers for preneoplastic lesions in liver. 21 refs., 3 tabs.« less