Effects of lanthanum on calcium-activated K+ currents and its kinetics in MC3T3 cells

Abstract

Using the whole cell patch-clamp technique, we studied the effects of La3+ on calcium-activated K+ currents and its kinetics of activation and inactivation in non-excitable MC3T3 cells. Our results showed that the calcium-activated outward K+ currents were promoted with increasing concentration of Ca2+ in the pipette solution and a voltage- and Ca2+-dependent manner. La3+ in the bath solution inhibited the currents in a concentration-dependent manner and the inhibition EC 50 was 8.23 ± 1.45 μmol/L. At the concentration of 50 μmol/L, La3+ significantly changed the V h of the activation curve and shifted the activation curve to more positive potentials, but shifted the inactivation curve to more negative potentials. It had no effect on the slope factor k of the activation and inactivation curves. Potassium currents inhibition could induce a series of physiological and molecular biological functions, presumably because of its ability to depolarize the plasma membrane and enhance cell excitability, resulting in increasing Ca2+ influx and cytoplast Ca2+ concentration. This process may be one of the molecular mechanisms by which La3+ affects the cell growth and function of MC3T3 cells.