RESUMO
Human stomach cancer cell line BGC-823 was treated by Tween 80 in combination with hyperthermia 39℃ to 43℃ for 20 to 100 minutes, respectively. The cell ultrastructure and succinate dehydrogenase (SDH) activity were studied at 0 hr, 48hr and 96hr after treatment respectively. Normal human fibroblast was used as control. The main changes of BGC-823 cells induced by hyperthermia were: dilation of endoplasmic reticulum, swelling of mitochondria, increase of fat droplets and decrease in SDH activity. After treatment at 43℃, the mitochondria showed vesicles or myelin figures and the polyribosomes tended to disaggregate. In nuclei, heterochromatin increased and the nucleolus become a dense homogeneous spot or annular ring. A few cells got necrosis. Effects of Tween 80 on BGC-823 cells were similar to that of hyperthermia. When Tween 80 combined with heating, marked synergic action was observed and the damage of membrane structure appeared earlier and more seriously. The effects of 41℃ combined with Tween 80 for 100 minutes were similar to that of 43℃ for 100 minutes alone. The critical temperature of hyperthermia for BGC-823 cells decreased to 41℃. The responses of the human fetal lung fibroblasts were slight and reversible. The results mentioned above suggested that the Tveen 80 enhanced the damage effect of hyperthermia on the tumor cells by decreasing the phase transition temperature of the tumor cells.