Introduction: Cyanide poisoning in man and animals is an important toxicological and environmental issue. Acute cyanide toxicity is lethal, resulting in death due to respiratory failure, while chronic cyanide exposure has been implicated in the aetiology of various health disorders. The aim of the current study was to determine the effects of chronic cyanide exposure on tissue enzyme activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and rhodanese in selected tissues of common carp. Methods: Common carp (Cyprinus carpio; total, n=45) were divided randomly into three groups of 15 each. Group I fish were reared in normal freshwater and served as the control. Fish in group II and IIIwere exposed to potassium cyanide for 14 days at doses of 0.2 mgL−1 and 0.4mgL−1, respectively. At the end of each exposure, enzyme activities in prepared tissue homogenates of liver, kidney, gill and brainwere determined using colorimetric methods. Results: Cyanide exposure (0.2 mgL−1) caused a significant (P<0.05) increase in AST and LDH activities in the liver as compared with the normal control group. Additionally, cyanide exposure (0.4 mgL−1) caused a significant increase in AST, LDH and rhodanese activities in the liver; AST activity in the brain; and LDH activity in the kidney as compared to group I. However, cyanide at the dose of 0.4 mgL−1 caused a significant decrease in ALP activity of kidney compared with the normal control group. Conclusion: The alterations in the enzymatic activities directly reflect the metabolic disturbances and cell damage in specific organs. The observed pattern of enzymes activity alterations will be discussed in relation to their biochemical function. The present data may be of value for further understanding the metabolic effects of chronic cyanide exposure as well as possible deleterious effects of the toxicant on examined tissues.

Keywords