ACRYLONITRILE-INDUCED REVERSIBLE INHIBITION OF URIDINE UPTAKE BY ISOLATED RAT INTESTINAL EPITHELIAL-CELLS

Isolated rat intestinal epithelial cells (IEC) were used to investigat e the mechanism(s) of acrylonitrile (VCN)-induced gastro-intestinal da mage. The isolated cells were 93% structurally intact for 60 min, as i ndicated by trypan blue exclusion. Uridine uptake by isolated IEC was linear from 6-20 min, after which a steady state was reached for up to 40 min. Exposure of isolated IEC to various concentrations of VCN red uced the ability of the cells to take up uridine in a concentration-de pendent manner. A concentration of 82 mu M VCN inhibited the [H-3]urid ine uptake of the cells by 50% (IU50). A time-course study indicated t hat the maximal inhibition of uridine uptake occurred at 15 min after exposure to VCN. The VCN-induced inhibition of uridine uptake was foun d to be reversible. IEC exposed to two sublethal doses of VCN (41 and 82 mu M) for 15 min regained normal uridine uptake activity within 50 min after removal of VCN. The present study provides a sensitive appro ach for the detection and evaluation of cytotoxic risk of sublethal do ses of the gastro-intestinal toxin VCN using IEC as target cells. The observed in vitro cytotoxicity of sublethal doses of VCN will be used to investigate further the mechanism of VCN-induced gastro-intestinal damage.