Protection of Tissue-culture Cells against Ionizing Radiation

Abstract

The radioprotective activity of a number of biological amines, disulphide compounds and thiols at various concentrations was tested in an in vitro system, based on the cloning technique devised by Puck et al. It was found that none of the biological amines (histamine, adrenaline, noradrenaline and serotonin) or disulphide compounds (cystamine and cystine) showed a protective activity. A defininitive protection on the other hand was observed with the thiol compounds (cysteamine, cysteine and AET). The protective activity of the latter compounds depended on the concentration which was used. Concentrations of 2–4 mM gave dose–reduction factors (DRF) between 1 and 2. At higher concentrations (cysteamine 32 mM and cysteine 128 mM) DRF's approaching 4 were obtained. The best protection with AET was observed at a concentration of 128 mM (DRF 2·2). The protection by AET was meliorated if higher serum concentrations in the culture medium were used. The best protection on a mM basis was provided by cysteamine. None of the compounds protected when applied after irradiation.