Ethanol enhances the calcium-dependent stimulus-induced release of endogenous dopamine from slices of rat striatum and nucleus accumbens in vitro.

When slices of striatum from the rat were preincubated for 40 min in calcium-free medium in vitro, the subsequent release of endogenous dopamine (DA) induced by 40 mM KCl was completely calcium-dependent, showing a maximal response in the presence of 1.5 mM CaCl2, and a half-maximal response in the presence of 0.5 mM CaCl2. In this calcium-dependent preparation, ethanol, at concentrations of 80-120 mM, significantly increased the KCl-induced release of endogenous DA from the striatum by 19-29%. This effect was not reproducible in calcium-replete incubation medium (2.0 mM CaCl2), suggesting that the phenomenon was calcium-dependent. Preliminary studies in the nucleus accumbens of the rat showed a similar increase (30%) in the calcium-dependent, KCl-induced release of endogenous DA in the presence of 100 mM ethanol.