Protective effect of glutathione against oxygen-induced growth inhibition of human diploid fibroblasts.

The reduced glutathione level in human diploid fibroblasts was increased by the addition of N-acetylcysteine or reduced glutathione ethylester into the culture medium, while it was decreased by the addition of L-buthionine-(R,S)-sulfoximine or diethyl maleate. The hyperbaric oxygen-induced reduction in colony-forming ability was prevented in the N-acetylcysteine- or reduced glutathione ethylester-treated cells, and enhanced in the L-buthionine-(R,S)-sulfoximine- or diethyl maleate-treated cells. The extent of the growth inhibition is well correlated with the cellular glutathione level. It is deduced that glutathione is an important safeguard against the oxygen-induced growth inhibition of human diploid cells.