Effects of preloading of stannous compounds on the distribution of 99mTc-pertechnetate

99MTc-pertechnetate distribution studies were performed in rabbits and mice following pretreatment between 5--336 hours with various routinely used stannous complexes (HSA, MAA, GHT, DTPA, PYPs) containing different amounts of Sn++ (0.17--15.0 mu mg/kg). Beyond a concentration of 0.26 mu mg/kg of Sn++ an alteration in 99mTc-ertechnetate distribution was observed. The red blood cell was found to be the most prominent target. An in-vivo reduction of 99mTc-pertechnetate apparently occurred by the presence of stannous ion within the red blood cell. Preloading time period between 5--24 hours did not alter the uptake of RBC/plasma ratio. Beyond that period it decreased slowly and still persisted up to 2 weeks following pretreatment. RBC/plasma ratio of 99mTcO4-increased with increased Sn++ content of various commercially available pharmaceutical kits.