The influence of cell volume changes on tumour cell proliferation.

Ion channels and cell volume control participate in a wide variety of cellular functions, including cell proliferation. According to the "pump-leak model" or the "double Donnan system", the cell volume is constant in physiological medium so long as the cell metabolism and the Na-K pump are not inhibited and the passive Na+ permeability is not dramatically increased. At short term, this model has been supported by a large number of experiments made on different cell types. However, at long term, it may be insufficient to describe the volume control because it does not take into account the fact that cells possess a large number of membrane transporters and interconnected volume regulatory mechanisms. In this review, we present recent results indicating that, in physiological conditions, ion channels may have important roles in cell volume control. Furthermore, we emphasize that cell proliferation and volume are phenomenologically correlated. On the basis of the macromolecular crowding theory, the possibility that the cell osmolyte and water content mediates this correlation is discussed.