Induction of growth in kidney epithelial cells in culture by Na+

The role of Na+ in the regulation of cell growth was examined in quiescent, high-density cultures of kidney epithelial cells of the BSC-1 line. The addition of NaCl to the medium increased the number of cells initiating DNA synthesis in a concentration-dependent manner after serum stimulation. In the presence of added NaCl, cells in confluent cultures grew to high density at an increased rate, whereas growth in sparse cultures was retarded. These results suggest that, in the presence of serum, Na+ can act as a mediator of the events that initiate cell proliferation.