Radioprotective effectiveness and toxicity of ATP, AET and serotonin applied individually or simultaneously to mice. III. Radioprotective effects of pair combinations.

The work reported was done as part of an intensive investigation on toxic and radioprotective properties of three substances, ATP, AET and serotonin, administered singly or in combination to mice, with a view to identifying optimal dose ratios for cocktails. Male C57BL mice were exposed to 850 R X-rays (LD100/11) following pretreatment with drug pairs at various dose ratios. Thirty-day survival was scored. For ATP-AET, protection increased with the amount of ATP in the combination; this pair was found to be most effective at an ATP-to-AET ratio of 11:1. A similar trend was observed with ATP-Serotonin, though only up to a certain ATP level beyond which no further increase in protective effect were produced; the most favorable ratio was of 24:1. A maximum synergistic action was displayed by the AET-Serotonin pair as compared to the other two pairs; its best ratio was of 4:1. Using probit analysis, a number of PD50 (protectant dose affording 50% survival in lethal irradiation) values were estimated for the three pairs of protective agents.