GLUTATHIONE DETERMINATION BY THE TIETZE ENZYMATIC RECYCLING ASSAY ANDITS RELATIONSHIP TO CELLULAR RADIATION RESPONSE

Large fluctuations in glutathione content were observed on a daily bas is using the Tietze enzyme recycling assay in a panel of six human cel l lines of varying radiosensitivity. Glutathione content tended to inc rease to a maximum during exponential cell proliferation, and then dec reased at different rates as the cells approached plateau phase. By re ference to high-performance liquid chromatography and flow cytometry o f the fluorescent bimane derivative we were able to verify that these changes were real. However, the Tietze assay was occasionally unable t o detect glutathione in two of our cell lines (MCH-U1 and AT5BIVA), al though the other methods indicated its presence. The existence of an i nhibitory activity responsible for these anomalies was confirmed throu gh spiking our samples with known amounts of glutathione. We were unab le to detect a direct relationship between cellular glutathione concen tration and aerobic radiosensitivity in our panel of cell lines.