Determination of intracellular reduced glutathione and glutathione related enzyme activities in cisplatin-sensitive and resistant experimental ovarian carcinoma cell lines

The level of GSH in ovarian carcinoma cells which were sensitive and resistant to cisplatin was serially determined following tumor removal from the animals, in addition, activities of GSH-reductase and GSH-S-transferase were assessed. The GSH level in the resistant line (O-342/DDP) was almost twice as high as that in its sensitive counterpart (O-342), when determined immediately following removal of the tumor (1.55 +/- 0.47 vs. 0.81 +/- 0.32 nmol/10(6) cells). Culturing the cells resulted in a decrease of GSH levels in both cell lines during the first 4 h. Thereafter, GSH levels in both cell lines increased up to 24 h. At this time the GSH level was higher in O-342 than in O-342/DDP. GSH-reductase activity in O-342/DDP cells was significantly higher than in O-342 cells when the enzyme was determined immediately after tumor removal; at the same time there was no difference in activity of GSH-S-transferase between two cell lines. After 24 h in culture, no significant difference between O-342 and O-342/DDP cells could be observed in the activity of the two enzymes.