Abstract
Yttrium administered to mouse has been found in relatively higher amount among soft tissues like liver and spleen. Our investigations were carried on the effect of internal exposure with β-radiation from 91Y distributed in spleen and liver.
The rate of retention of 91Y in spleen and liver after intravenous injection was about 20 times higher than after intraperitoneal injection, but the distribution pattern was similar in both cases, i.e., 91Y was retained homogeneously in liver, but predominantly in the red pulp region in spleen.
When mice were administered intravenously with 91Y at the rate of 3 μc/g. body weight, the splenic weight was reduced exponentially with absorbed energy, and similarly, DNA content of spleen was decreased with tissue dose. These effects could be understood from consideration of disappearance of lymphocytes. RNA content of spleen was sensitively decreased. On the other hand, both the tissue weight and the nucleic acid content in liver showed scarcely any change. These studies indicate that liver and spleen result in different response against internal β-radiation from 91Y, and thus, the general information that liver is radioresistant and spleen is radiosensitive can be fully accepted.
