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