On the relationship between accumulation of rare earth element in tumor and ionic radius

The accumulation of rare earth elements in the different organs of Ehrlich's tumor-bearing mice at 48 hours after intraperitoneal administration was measured by a Ge(Li) semiconductor detector. Accumulation of all the rare earth elements was the highest in the pancreas. Accumulation of 152Eu in the different organs of Ehrlich's tumor-bearing mice was very high. The accumulation of rare earth elements in Ehrlich's tumor was lower than the accumulation of 67Ga and 46Sc. The tumor-organ concentration ratio of rare earth elements was remarkably lower than the accumulation of 67Ga and 46Sc. However, the accumulation of 152Eu in Ehrlich's tumor was somewhat higher than that of 67Ga. The relationship between the accumulation and the carrier content was examined. The lower the carrier content was, the higher was the accumulation in different organs. However, the carrier effect of rare earth on the uptake in different organs elements was slight. The author postulated that the elements in which the ionic radius is similar to that of Mg(0.62 A) or Ca(0.99 A) are abundant in the tumor cell membrane, and they might pass through the tumor cell membrane much more easily than would the other elements. However, the result was negative. (JPN)