Effects of hexavalent chromium on enzymatic activities and transport process of intestinal brush border membrane of rainbow trout salmo gairdneri
Boge, G.; Bussiere, D.; Peres, G.
Water Research 22(4): 441-448
A new procedure has been developed to study the effects of hexavalent chromium (potassium dichromate) on brush border membrane functions of the intestines of living trout (alkaline phosphatase and maltase activities, glycine absorption). Manifold recycled perfusions were carried out with saline solutions containing the specific substrate, the hydrolysis of which liberates glucose (Bussiere et al., 1987). At the end of each period, glucose concentrations were determined using the glucose oxydase method (Hugget and Nixon, 1957). For the determination of alkaline phosphatase acteivity, glucose-1-phosphate (20 mM) was used as substrate rather than classic para-nitrophenyl phosphate because the product of its hydroloysis; para-nitrophenol, is rapidly absorbed by the intestine (Bussiere et al. 1987). Phloridzin (10-4 M) and KCl (150 mM), were added to the perfusates to prevent the glucose absorption. pH was adjusted to 10 with CHES (20 mM). For the determination of maltase activity, maltose (28 mM) was used as substrate in KCl (150 mM) solutions (10-4 M). pH was adjusted to 6.5 with MES (20 mM). The absortion of glycine by the intestine of trout was also determined in vivo using a perfusion technique (Peres et al., 1973). The intestinal lumen was perfused with a saline solution containing glycine 14C (0.5 mM) and buffered at pH 7.4 with HEPES 20 mM. The perfusate was recycled in the intestine during 30 min periods and non absorbed glycine was collected and measured.