Investigations of radio-yttrium (Y 90) metabolism : Studies of organ-distribution with special regard to the radioautographic method of demonstration and to paper electrophoresis under various experimental conditions

Abstract

By means of the usual measurement methods the organ distribution of Y 90 (Y 90Cl 3) was examined under various experimental conditions. Special emphasis was put on the inclusion of all organs. A further elucidation of Y 90 metabolism in regard to the question of structurally differentiated distribution following different methods of administration was achieved by using the radioautographic method of demonstration and also by using electrophoresis with subsequent registration of activity curves. In surveying the whole complex of our examination results, we see that Y 90 can by no means be called a “bone seeker” during the first 8 days, a period which is of great radiobiological importance. Within this period we never find more than 30 per cent of the dose in the skeletal system. On the other hand, there are high specific activities, depending on the method of administration, in the metabolically important organs, such as the pancreas, the hypophyses, and also in the genitals. The radioautographical pictures show that the variations in distribution are the result of the different transport mechanisms. Thus we assume that after intraperitoneal injection transport takes place mainly by way of the lymph. Furthermore, radioautography makes clear the formation of complexes on the part of yttrium and the nucleic acids; the relation between yttrium and the phospholipoids is also confirmed by a closer examination of the individual lipid fractions. From the point of view of radioactive contamination, the accumulation of Y 90 in the genitals, especially the ovaries, is important. The excretion of the radioisotope which we found in the lung seems to us important in so far as the lung is shown to function as an organ of the reticuloendothelial system; furthermore, the possibility of recontamination in animal experiments must be kept in mind. Thus our distribution studies of Y 90 produced results which are not only important in the question of incorporation-decorporation, but which also point to further medical and biochemical problems.