title: Correlation between the radiobiological oxygen constant, K, and the non-protein sulphydryl content of mammalian cells.
abstract: The value of the radiobiological oxygen constant K has been found to depend on the concentration of non-protein sulphydryl (NPSH) within the cell. Cells in the exponential phase of growth have a higher concentration of NPSH and a higher value of K than cells in plateau phase. Binding NPSH with N-ethylmaleimide reduced the value of K and conversely, addition of NPSH as dithioerythritol increased the value of K. K also rises with the same time course as NPSH increases, when plateau phase cells are replated into fresh medium. These results support the hypothesis that free-SH groups within the cell compete with oxygen to react with radiation damaged molecules.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000473:pathology / Q000532:radiotherapy; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D004229:Dithiothreitol / Q000494:pharmacology; D004307:Dose-Response Relationship, Radiation; D005033:Ethylmaleimide / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D008940:Mitotic Index; D010100:Oxygen; D011836:Radiation Tolerance; D013438:Sulfhydryl Compounds / Q000032:analysis
chemical_list: D013438:Sulfhydryl Compounds; D005033:Ethylmaleimide; D010100:Oxygen; D004229:Dithiothreitol