Tissue decorporation of polonium-210 in rats by DMPA.

Polonium-210 exposures, although rare, have occurred due to accidents in nuclear working environments. This alpha emitting radioactive element can bind thiols and thiol-containing proteins in vivo. Since thiol-containing chelating agents compete with many thiols for heavy metals, a number of these chelating agents have been investigated as protective agents against the lethal effects of 210Po and as tissue decorporating agents for it. Rats given 210Po (40 microCi/kg) ip had a median survival time (mst) of 39 days. The mst was increased to 106 days when N-(2,3-dimercaptopropyl)phthalamidic acid (DMPA), meso-dimercaptosuccinic acid (DMSA) or the Na salt of 2,3-dimercapto-1-propanesulfonic acid (DMPS) was administered sc (p less than .002). Decorporation studies were performed by giving rats 210Po (0.4 microCi) sc, followed by a series of thiol injections beginning one hour later. After 21 days, kidney levels of 210Po in rats given DMPA were only 28% of those of the untreated controls and significantly lower than those receiving DMSA, DMPS, N-acetyl-L-cysteine, or WR2721. After DMPA treatment, the 210Po levels of the spleen were 25% of the saline-treated control. DMPA appears to be a new and consistent decorporating agent for polonium-210.