BIOCHEMICAL AND ENZYMATIC ALTERATIONS DUE TO CHRONIC LEAD-EXPOSURE INTHE FRESH-WATER CATFISH, HETEROPNEUSTES-FOSSILIS

The effect of exposure to a sublethal concentration (6 mug/l) of lead nitrate on the levels of glucose and lactic acid in blood, glycogen an d lactic acid contents of liver and muscles, and the activities of hex okinase, lactate dehydrogenase, pyruvate dehydrogenase and succinate d ehydrogenase, in liver, kidney, intestine, gills and muscles of a fres hwater catfish, Heteropneustes fossilis has been studied at intervals of 60 and 120 days. The alterations produced were more marked after 12 0 days of exposure than in earlier stages. Blood glucose and muscle gl ycogen levels remained below normal level after 60 days of exposure. L actic acid level of the blood, liver and muscles, and glycogen content of the liver increased at this stage. The activities of all the four enzymes in gills and pyruvate and succinate dehydrogenase activities i n muscles decreased. After 120 days of treatment, blood glucose, liver and muscle glycogen level were elevated while lactic acid level decre ased in blood, liver and muscles. The activities of all the four enzym es examined were inhibited in liver, gills and muscles.