COMPARATIVE-ANALYSIS OF RADIOMETRIC AND AUTORADIOGRAPHIC METHODS IN THE INVESTIGATION OF DNA SYNTHETIC ACTIVITY OF TUMOR-CELLS IN-VITRO

DNA synthesis in cell cultures of Ehrlich ascites carcinoma (EAC) was studied by means of autoradiography and liquid scintillation radiometr y. The following parameters were compared for estimation of DNA synthe sis: a) total radioactivity of incorporated [H-3]thymidine registered by a liquid scintillation counter, b) labeling index (LI) reflecting t he relative number of cells which synthesize DNA, and c) mean grain co unt (MGC) indicating average intensity of DNA synthesis in the S-phase of the cell cycle. Kinetics of total radioactivity of incorporated [H -3]thymidine was determined to correlate better with LI. Changes in DN A synthesis in vitro were shown to be monitored with a higher level of significance by the radiometric technique, but autoradiography was mo re sensitive in some cases. Priority and informative value of the two methods were discussed. Autoradiography and liquid scintillation radio metry were concluded to be mutually complementary for investigation of DNA synthesis in tumor cells in vitro. Combination of the two methods was recommended for investigation of influence of cell proliferation inhibitors on DNA synthesis.