Uridine uptake inhibition as a cytotoxicity test for a human hepatoma cellline (HepG2 cells): comparison with the neutral red assay

This study describes a sensitive microassay for measuring cytotoxicity base d on the degree of inhibition of RNA synthesis in HepG2 cells. RNA synthesi s is measured by the kinetic uptake of radiolabeled uridine. A large number of compounds were tested in a wide range of concentrations. The concentrat ion required to induce 50% inhibition of HepG2 uridine uptake rates (IC50) was determined for each compound and used to rank its potency. These IC(50) s were compared with IC(50)s measured with the neutral red assay. 2-acetyla minofluorene, benzo[a]pyrene and methylnitrosourea were not cytotoxic ill t he neutral red assay. Uridine uptake was always inhibited at lower concentr ations than those required in the neutral red assay, suggesting that the ur idine uptake assay is a more sensitive indicator of toxic action than the n eutral red inclusion. Uridine uptake assay provides a rapid and quantitativ e method for assessing toxicity in a human cell line. Application of this m ethod to bottled spring waters are described. Due to its high sensitivity a nd reproducibility, this method provides a suitable tool for screening a gr eat number of samples and will be a helpful test for evaluating food safety and controlling the recycling process of wrapping materials. (C) 2001 Else vier Science Ireland Ltd. All rights reserved.