[Relationship between the glutamine synthetase and glutamate dehydrogenase pathways of detoxification of exogenous ammonia in fish].

Regularities of adaptation reactions of detoxication of exogenic ammonium in fish have been established. Under the pre-threshold level of the toxicant concentration level (0.05 mg/l) the function of the detoxication process is performed at the level of glutamine synthetase reaction mainly catalyzed by the enzyme cytoplasmatic form. The inhibition of both mitochondrial and cytoplasmic forms of the carp muscle glutamine synthetase by the mixed type was revealed under the effect of over-threshold concentrations of ammonium (0.1 mg/l). At the same time activity of NADP-glutamate dehydrogenase increases 2-4 times in the mitochondria and practically 10 times in the cell cytoplasm of the fish muscles and liver. The established regularity is considered as the adaptation of hydrobionts to the changes of ecological conditions of dwelling.