Effects of DTPA on the Deposition of65Zn,60Co and144Ce in Pregnant Rat and in Foetoplacental Unit

Abstract
65Zn, 60Co or 144Ce was injected intravenously into rats at various stages of pregnancy. Six hours later, DTPA chelate of non-radioactive Ca, Zn or Co was given intraperitoneally. Another group of pregnant rats received intravenous injection of 65ZnDTPA or 60CoDTPA. In both experiments, 24 hours after administration, the concentration of the radioactive material was determined in the dam's whole body as well as in foetuses, chorioallantoic placentae and yolk sacs. 65Zn and 60Co, which had been administered to the rats as DTPA complexes, were found not to pass from the dam's blood to the foetuses or to pass only in very minute amounts. This finding could be considered as an indirect indication that DTPA chelates do not penetrate the placental barrier. Nevertheless, the chelates injected intravenously into the dam early after an internal contamination, decrease the radionuclide content in the foetuses. No substantial effects of pregnancy on the effectiveness of the chelate in removing radionuclides from the body of rats were observed.