The Role of Intracellular Potassium in Cell Quiescence, Proliferation, and Death

This brief review explores the role of intracellular K⁺ during the transition of cells from quiescence to proliferation and the induction of apoptosis. We focus on the relationship between intracellular K⁺ and the growth and proliferation rates of different cells, including transformed cells in culture as well as human quiescent T cells and mesenchymal stem cells, and analyze the concomitant changes in K⁺ and water content in both proliferating and apoptotic cells. Evidence is discussed indicating that during the initiation of cell proliferation and apoptosis changes in the K⁺ content in cells occur in parallel with changes in water content and therefore do not lead to significant changes in the intracellular K⁺ concentration. We conclude that K⁺, as a dominant intracellular ion, is involved in the regulation of cell volume during the transit from quiescence, and the content of K⁺ and water in dividing cells is higher than in quiescent or differentiated cells, which can be considered to be a hallmark of cell proliferation and transformation.