Protection with combinations of hydroxytryptophan and some thiol compounds against whole-body gamma irradiation.

Protection of mice (as measured by survival at 30 days) against whole-body gamma exposure by prior treatment with combinations of hydroxytryptophan (HT) and some thiol drugs, is reported here. The combination of HT and aminoethylisothiuronium bromide hydrobromide (AET) was much more effective than HT alone against the effects of 10.5 and 12.5 Gy of gamma ray exposure. A combination of HT and beta-mercaptopropionylglycine (MPG) gave marked protection against a 10.5 Gy exposure but not against 12.5 Gy. The combination of HT with cysteine or cysteamine also provided reasonable protection against 10.5 Gy. The combination of HT and cystamine rendered a low level of protection against 10.5 Gy, but again it was better than HT alone. The thiol drugs by themselves in the doses used in combination were ineffective in rendering protection after whole body gamma ray exposure.