RADIOTOXICITY OF INCORPORATED [3H]THYMIDINE AS STUDIED BY AUTORADIOGRAPHY AND FLOW CYTOMETRY CONSEQUENCES FOR THE INTERPRETATION OF FLM DATA

Abstract

The radiotoxic effects of incorporated [3H]thymidine on proliferation kinetics of flash-labeled (30 min, 0.3 .mu.Ci/ml, 40 Ci/mM) mouse L-929 carcinoma cells in vitro were studied by means of autoradiography and flow cytometry. Flow cytometry was performed with the BUdR[5-bromodeoxyuridine]-33258 Hoechst technique using a new evaluation procedures. The labeled cells were delayed in their progression through the S and G2 + M phases, leading to mitotic delay. From autoradiographs, the fraction of labeled mitoses was determined and the ratio of labeled and of unlabeled mitotic cells to all cells was calculated. The radiotoxic effects were not evident from the FLM [frequency of labeled mitosis] curve, even if the ratio of labeled mitotic cells to all cells showed a highly distorted shape. A mathematical model describing the perturbed cell kinetics due to radiotoxic effects of the incorporated [3H]thymidine was developed. Many applications for interpretation of autoradiography, especially of labeled mitoses curves, exist.