Fura-2 measurement of cytosolic free calcium in rat brain cortical synaptosomes and the influence of ethanol

The effects of ethanol on resting and KCl-depolarized cytosolic calcium concentrations ([Ca 2+ ] i ) were measured in purified rat cortical synaptosomes using the calcium indicator fura-2. Ethanol (500–700 mM) significantly elevated the resting [Ca 2+ ] i by 13–25% in the presence of 100 μM external calcium. In the absence of external Ca 2+ , ethanol (50–200 mM) significantly increased [Ca 2+ ] i by 17–23%. Ethanol (200–700 mM) also significantly decreased KCl-induced rise in [Ca 2+ ] i (ΔK) by 40–82% in fura-2 loaded preparations incubated in the absence or presence of external calcium. Ethanol did not produce a significant change in ΔK at 50 and 100 mM concentrations. These results suggest that ethanol may cause an elevation in [Ca 2+ ] i via mobilization of intracellular calcium stores which may be linked to a calcium-dependent inactivation of voltage-sensitive calcium channels.