Decorporation of 241Am from mouse bone using Zn-DPTA, parathyroid hormone, and ammonium chloride

Twenty-four C57BL male mice, 124 days old, were each injected intraperitoneally with 0.08 μCi 241Am plus 0.02 μCi 85Sr in citrate solution. Three days later various decorporation combinations were started. All mice received repeated daily subcutaneous injections of ZnNa3DTPA (36 μmole/kg/day) from day 3 to day 25. Six mice also received a one-time subcutaneous injection of parathyroid hormone (4000 U.S.P. units/kg) on day 3; six mice received ammonium chloride (2 percent NH4Cl in their drinking water) from day 3 to day 25 and six mice received both parathyroid hormone (PTH) and NH4Cl. Retention of the 241Am and 85Sr was evaluated by sequential total-body counting of each mouse. At 5 days post radionuclide injection, the average percent biological retention +-- S. D. relative to that on day 3 (the start of decorporation therapy) was 52 percent +-- 3 percent for mice treated with PTH and 60 percent +-- 3 percent among mice not receiving PTH as part of their decorporation therapy. At day 25 the average retentions were 23 percent +-- 2 percent and 28 percent +-- 2 percent respectively. Most of the 241Am removal was due to DTPA, with PTH accounting for a slight increased removal. NH4Cl was ineffective in 241Am decorporation. None of the agents (DTPA, PTH, or NH4Cl) seemed to influence appreciably the excretion of 85Sr in mice