Summary
With exponentially growing EMT6 mouse tumour cells in vitro, we have compared the effects of a dose of ionizing radiation and different temperature-time combinations on the lengths of the cell cycle and of mitosis using time-lapse cinematography on individual cells. The radiation dose and various temperature-time combinations all produced 50 per cent lethality. The hyperthermia treatments between 42 and 45°C all caused a mitosis delay (MD) which was greater than that induced by ionizing radiation. The MD was greater with increasing temperature.
In contrast, hyperthermia also induced a mitosis lengthening (ML) but this was only of the same order of magnitude as radioinduced ML. The results argue in favour of different mechanisms underlying thermoinduced MD and ML.