Effect of cis-diaminedichloroplatinum (II) (cis-DDP) on the intracellular Na+/K(+)-ratio in K 562 leukemia cells as revealed by X-ray microanalysis.

Changes of intracellular ionic homeostasis are believed to play a role in the cytostatic action of cis-DDP. It has been observed by means of X-ray microanalysis that cis-DDP did not alter the intracellular Na+/K(+)-ratio of K 562 leukemia cells during incubation periods which lasted shorter than the average doubling time of the cells of nearly 15 h. After 24 h the treated cells displayed at least two main populations in the distribution histogram of the Na+/K(+)-ratio. The results indicated that the passage of cis-DDP through the plasma membrane by itself did not change the monovalent electrolyte balance at the early stage of its action in K 562 cells.