Effect of ethanol on [3H]nitrendipine binding to calcium channels in brain membranes

We examined the effect of ethanol on [3H]nitrendipine binding to rat brain membranes, to investigate the possibility that voltage-dependent calcium channels are involved in synaptic actions of ethanol. Ethanol inhibited specific [3H]nitrendipine binding with Ki = 460 mM, by decreasing binding affinity without altering the maximal number of sites labeled. At a lower concentration (100 mM), ethanol had no effect on inhibition of binding by verapamil or diltiazem. The high concentrations of ethanol required to produce alterations in [3H]nitrendipine binding suggest that ethanol and classical calcium channel antagonists influence calcium-mediated synaptic processes by separate mechanisms.