Protection by Sodium Hydrosulfite Against X-Ray-Induced Mitotic Inhibition in Grasshopper Neuroblast.

Abstract

In neuroblast cultures of the embryo of the grasshopper Chortophaga viridifasciata protection against X-ray-induced mitotic inhibition is conferred by pretreatment with sodium hydrosulfite. A concentration of 10-2 M sodium hydrosulfite almost completely prevents the inhibition of mitosis caused by 8 r. The mitotic inhibition caused by 32 r is only partially prevented by the same pretreatment. The dose-reduction factor at 32 r is 8. The rate of recovery is the same in the cultures that received 32 r and that were also pretreated with 10-2 [image] sodium hydrosulfite as in those that were irradiated but receive no pretreatment. The earlier recovery of the pretreated cultures is accounted for on the basis of less demonstrable inhibition of mitotic activity by the radiations. The primary damage responsible for mitotic inhibition at low doses, and at least partially at high doses, may be due to the oxidation of intracellular components by HO2 or similar oxidizing radicals whose formation is dependent on the presence of oxygen during irradiation.