Investigation sur la toxicodynamique du cyanure et sur sa biotransformation chez la truite arc-en-ciel (Salmo gairdneri)

Abstract

The exposure of rainbow trout (Salmo gairdneri) to 0.01, 0.02 and 0.03 mg HCN∙L−1 for 20 d demonstrated the biotransformation of HCN into thiocyanate which accumulated in the blood plasma which increased the duration of exposure to cyanide. Despite its transformation into thiocyanate, there is still a sufficient quantity of cyanide to inhibit cytochrome oxidase by 60–80% within the first 24 h of exposure. This level of inhibition remained stable during the 20 d of the tests and was the same at the three concentrations tested. This observation permits the prediction of effective concentration of free HCN inside the fish. The measurements of liver glycogen levels illustrate the Pasteur effect in the rainbow trout subjected to cyanide. During cyanide exposure, liver glycogen was rapidly used, particularly at 0.03 mg HCN∙L−1 whereas at 0.01 and 0.02 mg HCN∙L−1 the glycogen levels gradually came back to normal after 7–10 d of exposure.