Effect of hypertonic glucose in thermotolerant rat BT4An gliomas treated with combined hyperthermia and BCNU in vivo

The influence of hypertonic glucose i.p. on development of thermotolerance and thermochemosensitivity with BCNU in thermotolerant tumours, and on intratumoural pH alterations in previously unheated and thermotolerant tumours, was investigated in BT4An tumours grown on the hind foot of BD IX rats. Thermotolerance was induced with local waterbath hyperthermia (44d C/45 min) 24 h before start of test treatment. Hypertonic glucose immediately after priming hyperthermia did not inhibit development of thermotolerance, despite a significant reduction of pH by glucose. The pH reduction was less in thermotolerant tumours. Glucose administered before treatment of thermotolerant tumours did not change the growth rate of tumours treated with hyperthermia (44d C/45 min), BCNU (20 or 25 mg/kg i.p.) or thermochemotherapy with a low or high dose BCNU (10 or 20 mg/kg), in contrast to previous results, where glucose enhanced thermochemosensitivity of nonthermotolerant tumours.