Comparison of the protective action of glutathione and cysteamine on radiation-induced mitotic delay in cultured S-5 cells.

The protective effect of glutathione (GSH) and cysteamine (MEA) on radiation-induced mitotic delay in cultured mammalian L-5 cells was studied. Cells treated with 20 mM of GSH during irradiation with 2 Gy (200 rad) showed faster recovery of the mitotic index than control cells irradiated without chemical treatment; however, GSH had no effect on mitotic delay time. Inhibition of mitosis was observed with 80, 100, and 120 mM of GSH. Cells treated with 5 mM of MEA during irradiation also showed faster recovery of the mitotic index than the controls, but in addition the delay time was shortened. Progression of G2-phase cells treated with 5-fluorouracil to mitosis after irradiation was protected by MEA but not by GSH. Progression of S-phase cells labeled with 3H-thymidine to mitosis was accelerated by both agents during irradiation.