Elevated cytosolic calcium in cerebrocortical nerve terminals of rats during prolonged ethanol ingestion

Increases in cytosolic free calcium concentrations ([Ca++]i) may underlie acute neuronal degeneration during ischemic or anoxic episodes, seizures and excitotoxin treatment. With quin-2 and fura-2 fluorescent probes, we have obtained evidence for elevated [Ca++]i in cerebrocortical terminals of adult rats following chronic consumption of ethanol-containing liquid diets for "neurotoxic" durations. Compared to isocaloric carbohydrate-fed controls, ethanol-fed rats had significantly higher [Ca++]i in P2 synaptosomal fractions after 4 months of diet intake, and in purified cerebrocortical synaptosomes after diet ingestion for 10 months. In addition, [Ca++]i in the synaptosomal fractions of ethanol-fed rats from either exposure time were markedly resistant to K(+)-dependent potentiation. Persistently increased synaptic [Ca++]i and a blunted response to K+ depolarization following chronic ethanol ingestion lead us to associate impaired Ca++ homeostasis in the neurodegenerative processes of alcoholism.