Thermotolerance examined in vitro studies was reviewed in related to their kinetics, modifying factors and also the possible mechanisms. Heat treatments which reduce the survivals at same level at different temperature 42, 43, 44, 45 degrees C induces a same degree of thermotolerance and the thermotolerance decayed in same manner. These findings showed that thermotolerance induced by acute hyperthermia and that by chronic hyperthermia are not different in the nature. Examinations of heat sensitivities and kinetics of thermotolerance among different cell lines indicated that there is a possible relationship between the cellular sensitivity to heat and the magnitude of thermotolerance. The HSP has been found to be the most likely related factor in thermotolerance. But, their functions have not yet been clearly observed. Further research on HSP and thermotolerance is necessary to elucidate the possible mechanism of thermotolerance development.
