Accumulation of radioisotopes with tumor affinity. II. Comparison of the tumor accumulation of 67Ga-citrate and 201Tl-chloride in vitro.

The kinetics in tumor cells and various factors affecting the tumor accumulation of 67Ga-citrate and 201Tl-chloride were studied in vitro. 67Ga was taken up gradually by tumor cells and its excretion from the cells decreased with time. 201Tl was taken up rapidly by tumor cells. Its excretion was very rapid, indicating that the two nuclides had entirely different kinetics in tumor cells. The uptake of 201Tl by culture cells correlated with that of 42KCl and was inhibited by Ouabain. 201Tl was hardly taken up by nonviable tumor cells. These facts indicate that active transport involving Na-K ATPase is involved in the tumor accumulation of 201Tl. The uptake of 67Ga and 201Tl by tumor cells was not affected by the administration of anticancer agents. The uptake of 67Ga by tumor cells was dependent upon the concentration of transferrin in the medium, which apparently plays a role as one of the pathways of tumor accumulation of 67Ga.