The relationship between treatment duration and temperature for hyperthermia induced lethality of cultured murine cells. Influence of medium conditions.
The heat sensitivity and the time-temperature relationship of non-tolerant and thermotolerant M8013 cells treated at different pHs in either culture medium (including serum) or Hanks' salts solution (HBSS) were compared. The cells were growing asynchronously. Arrhenius plots for non-tolerant cells heated in culture medium pH 7.35 showed two linear parts below and above the transition temperature (Ttrans). The inactivation energies below and above Ttrans were respectively 2980 and 490 kJ/mole. With thermotolerant cells under the same conditions the inactivation energy was approximately constant over the range 42-46 degrees C at 890 kJ/mole. The cells were more sensitive to heat treatment at low pH or in HBSS. Moreover, it appeared that the expression of thermotolerance was strongly dependent on medium conditions: the thermotolerance ratio (TTR, ratio between slopes of survival curves of thermotolerant and normal cells) was much lower at low pH or in cells heated in HBSS. Generally a high TTR observed in experiment with fractioned hyperthermia at temperatures above Ttrans correlated fairly well with a high inactivation energy below Ttrans from the Arrhenius plot derived from data from experiments with the same cells that were not made thermotolerant before treatment.
Haveman
J
J
Department of Radiotherapy, University of Amsterdam, The Netherlands.
Hart
A A
AA
D000818:Animals; D001769:Blood / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D003470:Culture Media / Q000378:metabolism*; D006358:Hot Temperature / Q000009:adverse effects*; D006863:Hydrogen-Ion Concentration; D051379:Mice; D013997:Time Factors
D003470:Culture Media