Aluminum enhances the voltage activated sodium currents in the neurons of the pond snail Lymnaea stagnalis L.

1. The effects of aluminum on voltage activated sodium currents (VASCs) were investigated by using the conventional two-electrode voltage clamp technique in Lymnaea stagnalis L. neurons. The peak amplitude, kinetics, and voltage-dependence of activation and inactivation of the sodium currents were studied in the presence of 5-500 mu M AlCl3, at pH = 7.7. 2. There was a significant concentration-dependent increase in the peak amplitude of sodium currents after Al treatment, ED50 = 67 mu M. The threshold concentration of the enhancement was 50 mu M. The maximal peak increase of 143% was caused by a 500 mu M aluminum. The action of aluminum on VASCs developed slowly, and it is not recovered by washing within 20 min. 3. There was little alteration of the voltage-dependence of the current. It was not a significant effect on the activation- and inactivation time constants of I-Na, but the steady-state inactivation curve shifted to negative direction on the voltage axis in the presence of Al. 4. The leak currents were not influenced by aluminum up to the highest concentration applied.