The kinetics of thermotolerance decay and cell proliferation was determined following initial heat treatments of 10 or 30 min at 44° in Chinese hamster ovary cells. Thermotolerance was more pronounced following the longer initial heat treatment, but maximal tolerance developed by 10 hr in both cases. After its maximal development, tolerance decayed in an exponential manner. The half-times of tolerance decay were 11 or 16 hr following 10- or 30-min pretreatments. Thermotolerance was apparent in the progeny of heated cells for 4 to 5 postheat cell generations.
This work was supported by grant CA22860 awarded by the National Cancer Institute, Department of Health, Education, and Welfare.