The combined action of gamma irradiation and hyperthermia on the structure of the cell population in the Chinese hamster

: A change in the structure of FAF-28 Chinese hamster cell population occurred during 24 h following gamma-irradiation or hyperthermia heating, or the effect of both factors was studied by flow cytofluorometry. With radiation delivered immediately after heating the distribution of cells among cycle phases was nearly the same as with hyperthermia alone: the share of cells at the S-phase was invariable during the first 4-6 h, then it slowly diminished; at G1 it slowly decreased and at G2 increased. When irradiation preceded heating the pattern of cell redistribution during the first hours was the same as that with radiation alone: the "wave" of transition from G1 to S phase was the same, but shorter in amplitude and longer in time; then cells were accumulated at G2+M and remained there for 24 h. Thus, of the two factors applied, the first was the major one in changing the cell population structure during the first hours after treatment. In 24 h the result was the same, that is, the considerable accumulation of cells at G2+M.