ACTION OF CYPERMETHRIN ON TISSUE TRANSAMINATION DURING NITROGEN-METABOLISM IN CYPRINUS-CARPIO

Freshwater fish, Cyprinus carpio, was exposed to sublethal concentrati on (3 mu g liter(-1)) of cypermethrin for 5 and 10 days to examine the changes in the transamination process during the formation of nitroge nous end products in four functionally different tissues, namely, gill , liver, brain, and muscle, Increases in total and soluble protein con tents were noticed in all the tissues of exposed fish with a decrease in free amino acids and protease activity, Activity levels of both the transaminases, aspartate aminotransferase and alanine aminotransferas e, and glutamate dehydrogenase were elevated, indicating active transa mination and oxidative deamination, Attenuation of ammonia was consist ent in both treatment groups. However, urea level decreased at the 5-d ay exposure period but increased by Day 10, manifesting the conversion of toxic ammonia to urea, Glutamine content was consistently raised u pon exposure to the toxicant, In support of this, increases in glutami ne synthetase and suppression of glutaminase were noticed, It clearly indicates that ammonia is not stored in the tissues in spite of active oxidative deamination when the fish is in a polluted environment. All the observations made demonstrate that the fish has adopted more than one compensatory mechanism during the process of transamination of ni trogenous products. (C) 1996 Academic Press, Inc.