[Thermotolerance in normal and tumor tissues]

Thermotolerance, or increased resistance of tissues to hyperthermia following a prior heat treatment, has been demonstrated not only in normal but also in tumor tissues. The kinetics of thermotolerance depends on the prior heating conditions, i.e. the greater the initial heat damage, the greater is the magnitude of thermotolerance and the longer is the time to reach maximum and the time to decay. Although thermotolerance develops less extensively in cultured cells in low pH medium and average tumor tissue pH is lower than the normal tissue pH, the magnitude of thermotolerance in tumor thus far examined is at least equal to that in the normal tissues. It is known that development of thermotolerance is well correlated with enhanced synthesis of heat shock proteins (HSPs). Recently, we purified HSP 70 (70 kilo dalton HSP) and prepared a rabbit antiserum against the HSP 70. In our preliminary experiments, HSP 70 could be detected and analyzed quantitatively not only in cultured cells but also in normal and tumor tissues by immunoblotting using the antiserum.