Effect of ethanol and aging on histamine release and membranes of mast cells

The effects of ethanol on histamine release from mast cells were compared to ethanol's effects on membrane order of mast cell membranes and synaptosomes in young (6 month) and old (24 month) Fischer 344 rats. Concanavalin A (con A) stimulated histamine release in a concentration dependent manner. Ethanol (10-500 mM) inhibited con A stimulated release while having no effect on nonstimulated release in both young and old rats. Ethanol's effect on membrane order of synaptosomes and mast cell plasma membranes was estimated by measuring the fluorescence polarization of diphenylhexatriene. Ethanol (10-500 mM) decreased the polarization of synaptosomes to the same degree in young and old rats. The polarization of mast cell membranes was also decreased by ethanol but to a greater degree than synaptosomes. The ethanol induced changes in polarization correlated (r2 = 0.99) with ethanol's inhibition of con A stimulated histamine release from mast cells. These findings suggest that mast cells may be more sensitive to membrane disordering by ethanol than synaptosomes. In addition, we have demonstrated that mast cells may be a useful model system for studying ethanol effects on stimulus-secretion coupling. No differences were found between rats 6 and 24 months for histamine release (with or without ethanol) or membrane order of mast cells or synaptosomes.