Radioprotective Action of SH Compounds Ⅲ. Effects of Aminoethyliosothjuronium Br. HBr, Cysteamine and 2-Mercaptopropionylglycine Against Mitotic Delay Induced By X-Rays.

Protection by SH compounds (MPG, cysteamine and AET) against the mitotic delay induced by X-irradiation in Ehrlich ascites tumor cells was studied. With exposure to 200 rads, the mitotic delay time and its recovery of the group treated with SH compounds (0.5 mg MPG, 2 mg cysteamine and 3 mg AET) were similar to those of non-treated group up to 12 hours after irradiation, but at 12 hours and rater the mitotic index of the groups treated with SH compounds was at a much higher level. The recovery rate from the mitotic inhibition became faster by increasing the concentration of the SH compounds (4 mg cysteamine or 6 mg AET) injected. Similar effects of SH compound were observable in the case of 400-rad irradiation. Increasing the concentration of the SH compound (4 mg cysteamine or 6 mg AET) treated, the recovery of mitosis was accelerated remarkably. From these data, it is suggested that the SH compound has a differential protective effect on mitotic delay the cell cycle.