A QUANTITATIVE-ANALYSIS OF THE ROLE OF K+-CHANNELS IN MITOGENESIS OF NEUROBLASTOMA-CELLS

The role of K+ channels in mitogenesis was studied on mouse neuroblastoma cells by analysing the effects of various chemical agents on the whole-cell K+ current and the cell proliferation. The outward current recorded during depolarization on undifferentiated cells was made up of a small and slow inactivating K+ current. Foetal calf serum, which is mitogen for neuroblastoma cells, shifted in opposite directions by 7-10 mV peak activation and steady-state inactivation-voltage curves of the K+ current. The resulting effect was an increase in K+ conductance. The effect on the resting K+ flux of the classical K+ channel blockers tetraethylammonium, 4-aminopyridine and capsaicine, the anticancer agent tamoxifen, the heat inactivated serum and the increase in external K+ concentration were estimated from their effects on the K+ current. The cell proliferation was determined under the same conditions. The results indicate that cell proliferation is correlated to the resulting K+ flux. It is supposed that mitogenesis is controlled by the intracellular Na+ concentration which, via a cell volume regulation, is a function of the K+ flux. A quantitative model is developed on the basis of these hypotheses.