Saturable ethanol binding in rat liver microsomes

The binding of ethanol to rat liver microsomes is shown to be saturable at clinically relevant ethanol concentrations, whereas this effect is not observed in extracted microsomal phospholipids. Brief exposure of the microsomes to heat abolishes saturable ethanol binding. Equilibrium binding data analysis, although only approximate in this context, suggests the presence of at least two groups of specific sites: high capacity sites with affinities near the pharmacological range and low capacity sites at lesser levels. The results indicate that the specificity of ethanol for tissue is considerably greater than previously recognized.