Alcohol dependence at the cellular level: Effects of ethanol on calcium homeostasis of IM-9 human lymphoblast cells

Objective: Increased intracellular calcium level ([Ca2+](i)) was previously observed in peripheral blood mononuclear cells of alcoholic patients under withdrawal. To determine whether this change in [Ca2+](i) is due to direct effect of ethanol on blood cells and shows adaptation of these cells to alcohol, we examined the effect of alcohol on IM-9 human lymphoblast cultures. Method: [Ca2+](i) of IM-9 lymphoblasts, after acute and chronic alcohol treatment as well as alcohol withdrawal, was measured fluorometrically using Quin2 as a Ca2+-indicator. Results: Acute ethanol treatment induced a rapid, transient increase in intracellular calcium concentration in a dose-dependent manner. During chronic ethanol (50mM) administration, after the first 24 hours, basal [Ca2+](i) was significantly lower (44 +/- 8% of control, p < .025), whereas from the fifth day [Ca2+](i) was significantly higher (415 +/- 59% of control on the sixth day, p < .01) compared with untreated cells. After a 3-day ethanol (50mM or 100mM) treatment, elimination of alcohol from the medium caused elevation in [Ca2+](i). After 24-hour ethanol withdrawal, the addition of alcohol decreased the elevated [Ca2+](i) of alcohol-adapted cells to the resting level of control cells. Similar results were observed when verapamil, diazepam or haloperidol were applied. Moreover, when ethanol or these agents were administered at the beginning of alcohol withdrawal, they could prevent the increase in [Ca2+](i). Conclusions: These results suggest that alcohol dependence can develop at the cellular level, and that changes in calcium homeostasis, likely due to direct effects of ethanol on ion channels, may play a central role in processes leading to adaptation of cells to alcohol.