Modification of Nifedipine Inhibitory Effect on Calcium Spike and L-Type Calcium Current by Ethanol in F1 Neuron of Helix aspersa

There is strong evidence demonstrating that nifedipine dissolved in ethanol selectively inhibits only L-type Ca2+ current. In addition, acute ethanol exposure reduces voltage-dependent calcium currents. In the present study, we investigated the antagonistic effect of fixed concentration of nifedipine dissolved in different concentration of ethanol on L-type Ca2+ current. In a Na+-K+ free solution, nifedipine dissolved in 60 and 120 mM ethanol decreased resting membrane potential of Ca2+ spikes and caused a significant reduction in amplitude, duration and an increase in threshold of Ca2+ spikes. Furthermore, Ca2+ current was inhibited by ethanol in a concentration-dependent manner, so that the reduction of L-type Ca2+ current by nifedipine/60 and 120 mM ethanol was statistically significant. Meanwhile, ethanol concentration-dependent response of Ca2+ currents was observed at its late component in more positive potentials. These results may be consistent with ethanol-dependent inhibition of L-type Ca2+ currents and ethanol-dependent enhancment of a Ca2+-activated potassium current