Studies on the67Ga uptake mechanism by Ehrlich ascites tumor cells

In order to obtain more information concerning the mechanism of Gallium (⁶⁷Ga) accumulation in malignant tissue, an investigation was carried out using Ehrlich ascites tumor cells. Chlorpromazine, a phospholipid stabilizer decreased the uptake of⁶⁷Ga and Calcium 45 (⁴⁵Ca) by the cells at low dose, but increased them at high dose. On the other hand, the uptake of both radionuclides by the cells was inhibited by ruthenium red, a Ca ATPase inhibitor in a dose dependent manner. The time course of⁶⁷Ga and⁴⁵Ca uptake were quite different from each other. Moreover, the subcellular distribution patterns of⁶⁷Ga and⁴⁵Ca were also different from each other;⁶⁷Ga accumulated in the lysosomal fraction and⁴⁵Ca mainly in the mitochondrial fraction. These results suggest that there may be a commonality for⁶⁷Ga and⁴⁵Ca uptake by the tumor cells, whereas the behaviour of these two radionuclides in the cells is dissimilar.