REGROWTH AND RADIATION SENSITIVITY OF QUIESCENT CELLS ISOLATED FROM EMT6/RO-FED PLATEAU MONOLAYERS

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  • 1 January 1985
    • journal article
    • research article
    • Vol. 45  (3) , 1020-1025
Abstract
A quiescent [denoted as Q(G0/G1)] subpopulation was isolated from EMT6/Ro-fed plateau monolayers by centrifugal elutriation. The median Coulter volume of these cells was significantly smaller than that of the original population from which they were elutriated. Using 2-step acridine orange staining and dual parameter flow cytometric analysis, over 95% of quiescent cells were found to have G1 DNA content and 80% of the cells had a decreased RNA content as compared to rapidly proliferating exponential G1 cells. After labeling for 24 h (2 doubling times) with [3H]thymidine, < 2% of the quiescent cells incorporated [3H]thymidine as measured by autoradiography. The colony-forming efficiency of these cells was not significantly different from that of exponential cells. When such Q(G0/G1) cells were replated in fresh medium at a lower density, there was a lag time of 30 h before any increase in cell number was detected, after which the cell-doubling rate matched that of exponential culture. Results obtained from the radiation dose-response curves showed that quiescent (G0/G1) cells were more radiosensitive than exponential G1 or unseparated fed plateau cells.