Alterations in the cellular DNA and protein content determined by flow cytometry as indicators for chemically induced...

Cellular DNA and protein content were determined simultaneously in freshly isolated fibroblast-like rat cells by flow cytometry. After exposure to doxorubicin, nitrofurantoin, propranolol and practolol at a low, tissue like oxygen concentration (5% O2), drug-induced alterations in cell cycle kinetics, in the distribution of DNA and in the protein content of G1-phase cells (nucleus/cytoplasm ratio) were analysed. Optimal exposure time (5 or 24 h) and recovery interval (24 or 48 h) were determined. Variation in the exposure time and recovery period can affect cell cycle kinetics both qualitatively and quantitatively, whereas the distribution of DNA and protein content are affected quantitatively only. A 24-h exposure combined with a 24-h recovery period proved to be the most efficient approach. Each of the tested chemicals induced a specific, dose-dependent pattern of altered cellular DNA and protein content. Comparison with results obtained in other genotoxicity tests, and with data reported earlier, showed that this two-parameter protocol can be used to recognize and to characterize chemicals as clastogens, or as compounds with a combined cytostatic/clastogenic activity, or as spindle-poison-like compounds.