Spontaneous calcium release induced by ethanol in the isolated rat brain microsomes

Ethanol-induced neurotransmitter release in unstimulated synaptosomes was found to be independent of extrasynaptosomal Ca2+ concentration, indicating a redistribution of intracellular Ca2+. The effects of alcohol on microsomal Ca2+ uptake and release were studied. In vitro addition of 100 mM ethanol had no effect on ATP-dependent Ca2+ accumulation in the microsomes. However, the same amount of ethanol released 25% of total accumulated Ca2+ from the microsomes. Ethanol induced Ca2+ release in a concentration-dependent manner over the range 30 mM-500 mM. The amount of Ca2+ release increased with higher alcohols. The effect of alcohol was temperature-dependent and inhibited at 0 degrees C. These results indicate that the known stimulatory effects of ethanol on resting release of neurotransmitters may be due to the microsomal release of Ca2+.