[Effects of hexavalent chromium at non-lethal concentrations on the enzymology of the intestine of Salmo gairdneri and Dicentrarchus labrax (Pisces)].

Abstract

Effects of non lethal concentrations of hexavalent chromium on intestinal enzymology of Salmo gairdneri and Dicentrarchus labrax (Pisces). The effects of an exposure to potassium dichromate on intestinal enzyme activities (Alkaline phosphatase, maltase, leucine amino peptidase and ATPases) have been studied on a fresh water fish (Salmo gairdneri) and a salt water fish (Dicentrarchus labrax). Fish were exposed at seasonal temperatures (13 or 21 degrees C) to toxic concentrations equal to 1/10 of the 24 h-LC 50 (i.e. 18 mg/l Cr for trout and 5 mg/l Cr for bass) during respectively 13 and 21 days. Intoxicated trout stopped feeding and showed a decrease in their intestinal weight at the end of the experiments. A decrease of brush border membrane activities (Alkaline phosphatase, maltase and leucine amino peptidase) were also observed. These alterations have been interpreted as the consequence of the chromium induces fasting. Intoxicated bass showed no alterations of their feeding habits. Two specific effects of chromium on enzyme activities have been found: a severe decrease of the alkaline phosphatase activity and an increase of the Na/K ATPase activity. These enzyme activities could be useful indicators of chromium intoxication in marine fish.