Pathobiochemistry of Ammonia in the Internal Environment of Fish (Review)

Abstract

In this study, the origin and pathways of detoxication of ammonia in the body of fish are analysed. Ammonia is toxic for an organism even in trace amount. The role of direct deamination of amino acids such as histidine, serine, asparagine and glutamine is emphasized with regard to ammonia production, the functional association of transamination and deamination is reflected in a transdeamination reaction, where the central role is played by the enzyme glutamate dehydrogenase. Furthermore, less known sources of ammonia occurring during natural restoration of body cells and tissues are discussed. Particularities of biochemical processes in fish, such as the non-existence of ureosynthetic cycle along with a sudden change of environmental conditions can easily disturb the balance between production and excretion. If the detoxication abilities of fish are exceeded, ammonia acts as a toxicant, thus leading to accidental mortalities of fish.