Protection of cholinesterase by ethanol against inhibition by organophosphates in vitro.

Because many of the organophosphates used as anticholinesterases are insoluble in water, it is usual to dissolve them in water-miscible organic solvents in order to study their inhibition of the enzyme both in v&o and in vivo. Ethanol is commonly used for this purpose (1, 2), and, because it is an inhibitor of the enzyme, the control samples are treated with a similar level of the solvent. The extent of inhibition by the organophosphate is then obtained by reference to the alcohol-treated control, and the results are considered as corrected for the presence of alcohol and therefore comparable with results for water-soluble inhibitors obtained in ethanol-free solutions. In order to determine the validity of this assumption, experiments were carried out with several water-soluble organophosphates both with and without ethanol, and it was found that the solvent interferes strongly with the inhibition process.