Enzymological and biochemical changes produced by chronic chromium exposure in a teleost fish, Channa punctatus

The chronic toxic effects of chromium (2.6 mg/1) on the carbohydrate metabolism of a teleost fish, Channa punctatus were examined after 60 and 120 days of exposure. After 60 days the lactic acid content of blood and muscles was increased but liver lactic acid content decreased. Liver glycogen was also depleted. The activity of lactate dehydrogenase was inhibited in liver and kidney. Pyruvate dehydrogenase and succinate dehydrogenase activities were also inhibited in all the tissues except muscles. Fish were hypoglycemic and hyperlactemic after 120 days of exposure to chromium. The glycogen content increased in liver but decreased in muscles. Lactate dehydrogenase activity was inhibited in all the six tissues. The activity of pyruvate dehydrogenase decreased in liver, intestine, gill and muscles. In muscles succinate dehydrogenase activity was elevated but inhibition was recorded in other tissues.