Effects of D,L-buthionine-S,R-sulfoximine on cellular thiol levels and the oxygen effect in Chinese hamster V79 cells.

The role of glutathione (GSH) and total non-protein thiols (NPSH) in repairing radiation-induced free radical damage incurred under aerated and hypoxic conditions was investigated using Chinese hamster V79 cells cultured in vitro. GSH and NPSH levels were depleted in V79 cells of varying cell densities using the gamma-glutamyl-cysteine-synthetase inhibitor, D,L-Buthionine-S,R-sulfoximine (BSO). A small change in hypoxic cell radiosensitivity could be attributed to the loss of GSH while depletion of thiols to lower levels affected both aerated and hypoxic cell radiosensitivity, resulting in no change in the OER. Only a long term incubation with BSO produced a large change in the OER, by which time many other biochemical pathways using GSH and amino acids are likely to be affected.