Modification of survival of gamma irradiated mice by adenosine nucleotides

The administratio prior to irradiation of adenosine triphosphate (ATP) or other adenosine nucleotides, singly or in combination, increased the radioresistance of mice. Post-irradiation treatment with the adenosine nucleotides had no effect on the survival of the irradiated mice. Dose reduction factors of 2.32 could be obtained by pretreatment of mice with the following combination of protective agents: S-2(4-aminobutylamino)ethyl phosphorothioic acid(WR 2822), cysteamine (MEA) and ATP. Since cyclic AMP levels were unchangd in the spleen or gut by administration of cysteamine and other protectors it is unlikely that the increase in preotection was due to changes in cyclic AMP levles. The calcium salt of ATP provided a higher level of protection than the ATP alone, indicating that the protective mechanism of ATP is probably not related to anoxia.