Ethanol and voltage- or receptor-mediated increases in cytosolic Ca²⁺ in brain cells

Dissociated brain cells were isolated from newborn rat pups and loaded with fura-2. Different mechanisms for stimulating increased free intracellular Ca²⁺ concentrations ([Ca²⁺]_i) were examined in the absence and presence of ethanol. KCl, carbachol, and kainate concentration-dependently increased [Ca²⁺]_i. Quisqualate also elevated [Ca²⁺]_i but did not produce clear concentration-dependent increases. KCl, carbachol, and quisqualate responses reached peak levels within 10-30 s and then desensitized within 90 s. However, kainate-stimulated increases in [Ca²⁺]_i plateaued and did not decline after 90 s. Of these different [Ca²⁺]_i-mediated processes, only 60 mM KCl stimulation was significantly inhibited by 100 mM ethanol, while lower KCl concentrations were not affected. Carbachol-induced release of intracellular Ca²⁺ and activation of non-NMDA (i.e., kainate, quisqualate) excitatory amino acid receptor-operated cation channels were also not significantly inhibited by 100 mM ethanol. Thus, in acutely dissociated brain cells from newborn rats, only Ca²⁺ influx via voltage- and, as reported previously, NMDA-operated Ca²⁺ channels were sensitive to ethanol inhibition.