Flow cytometry for analyzing changes in irradiated and heated HeLa S3 cells.

In the present study, we have compared the distribution in various phases, DNA content, cell survival and ultrastructure of HeLa S3 cells after irradiation and/or hyperthermia. After 220 KV X-ray irradiation, the Do of the survival curve was 0.94 Gy, Dq was 1.3 Gy, and N was 4.26. After Ir-192 gamma-ray irradiation, the Do of the survival curve was 2.26 Gy, Dq was 3.9 Gy, and N was 5.7. The Do of the survival curve of HeLa S3 cells after treatment at 43.5 degrees C and 44 degrees C was 2.2 min and 1.6 min, respectively. Ultrastructural changes were also observed. The marked increase of the DNA content after 6 Gy irradiation corresponded with changes of distribution in various phases, which indicated a delay in the G2 + M phase. The survival fraction after 6 Gy irradiation was less than 1%. The changes of cell cycle distribution after Ir-192 irradiation were similar to those seen after X-ray exposure. The delay of G2 + M phase after hyperthermia was dose-dependent. An obvious delay of the G2 + M phases was also observed at 24 h after treatment with X-rays plus hyperthermia.