TRANSFERRIN-MEDIATED UPTAKE OF PLUTONIUM BY SPERMATOGENIC TUBULES

Using isolated rat seminiferous tubules as an in vitro model, we have found that Pu-238 can cross the blood-tubule barrier and accumulate wi thin tubules in a time dependent manner. Furthermore, similar to Fe-59 , tubule Pu-238 uptake was inhibited by the addition of excess transfe rrin, suggesting that plutonium may utilize the physiological iron-tra nsferrin pathway to cross the blood-tubule barrier. However unlike Fe- 59, Pu-238 was only transiently associated with the tubules, suggestin g differences in the intracellular processing og these radionuclides. The assumptions made in the estimation of doses to the human testis fr om incorporated plutonium are considered.