ALTERATION OF HEAT SENSITIVITY BY INTRODUCTION OF HSP70 OR ANTI-HSP70ANTIBODY IN CHO CELLS

1. An electroporation system employing an oscillating electric pulse a nd centrifugal force was used to introduce HSP70 or anti-HSP70 antibod y into Chinese hamster ovary cells. 2. There was a 1.5- or 1.9-fold in crease in the amount of intracellular HSP70 by electroporation in the presence of 0.75 or 1.5 mg/ml, respectively. 3. Cells electroporated w ith HSP70 became resistant to hyperthermic killing; i.e. the survival increased 6-7-fold from 1.2 x 10(-2) to 7-8 x 10(-2)-heating at 45.5-d egrees-C for 20 min. 4. In contrast, introduction of 1 mg/nil anti-HSP 70 antibody sensitized cells to hyperthermic killing; i.e. the recipro cal of the survival slope was decreased from 1.68 to 1.25 min. 5. Thus , our results support the hypothesis that HSP70 plays an important rol e in heat resistance.