[Effects of intracellular Na+/K+ ratio on histone gene expression in ascitic cells of leukemia P-388 and Ehrlich cancer].

The intracellular Na+/K+ ratio was studied for its effect on histone genes expression in Ehrlich carcinoma and leukemia P-388 ascites cells. After equilibration with certain Na+/K+ ratio buffers at 0-4 degrees C the cells were treated during 1 h at 37 degrees C with ouabain added to the corresponding medium. Then total RNAs were extracted and analyzed by the reaction of blot-hybridization with histone genes cluster in plasmid p604. The maximal level of histone genes expression in leukemia P-388 cells was observed under conditions when intracellular Na+/K+ ratio corresponded to those at S-phase of the mitotic cycle. In Ehrlich carcinoma ascites cells the expression of histone genes was not dependent on the Na+/K+ ratio. A conclusion is drawn that the intracellular ratio of monovalent cations is one of the possible mechanisms which regulates the gene expression during the mitotic cycle.