Hyperthermia in a Differentiating Murine Erythroleukaemia Cell Line: II. Effect of Heat on Haem Induction by Radiation

Summary Friend erythroleukaemia cells (FELC) were induced to a haem-producing state by X-rays. The percentage of haem positive cells was maximum for doses between 10 and 15 Gy. Heat treatment at 42·0°C or 45·0°C during or after irradiation inhibited haem induction whereas heating before irradiation enhanced it. Incubation at 37°C between heating and irradiation resulted in a decline in induction levels, indicating repair of heat damage that interacts with X-ray damage. Incubation at 37°C between irradiation and heating did not result in changed haem induction levels, indicating a lack of repair of radiation damage that could interact with subsequent damage produced by heating.