Due to the high affinity of biotin to Av or SA. We labelled a biotin derivative(DTPA-biotin) with ~153Sm and then bound this 153Sm labelled DTPA-biotin to Av orSA. The in vivo kinetics and biodistribution of 153~Sm labelled
Av
SA andDTPA-biotin were studied in the rat and mice. The results demonstrated that153Sm-Av cleared from the blood rapidly with high liver and renal uptake; ~153Sm-SAcleared from blood slowly with high retention in liver
spleen and kidney
whereas153Sm metabolize more fast
and excreted mainly through the kidney. Thereby
thebiodistribution difference of SA and Av mentioned above provided an expermentalbasis for the selection of different components of A-V system in pretagetingradioimmuno imaging and radioimmunotherapy.