Effects of extracellular Ca2+ and Mg2+ on nucleic acids and proteins syntheses by tumor and normal liver cells.

The effects of increasing extracellular concentrations of Ca2+ and Mg2+ on the uptake of 14C-thymidine, 3H-uridine and 14C-leucine by Novikoff hepatoma and normal liver cells have been studied. Increasing concentrations of Ca2+ stimulate all the three incorporations while Mg2+ exhibits an inhibitory effect. Liver cells presented a higher cation permeation induced by the extracellular concentration than hepatoma cells which also seems to explain the quantitative differences observed in the studied syntheses. The importance of the extracellular cation-cell membrane interaction in these effects is discussed.