Ethanol metabolism in alcohol dehydrogenase deficient deermice is mediated by the microsomal ethanol oxidizing system, not by catalase.

The participation of the microsomal ethanol oxidizing system (MEOS) and catalase in total ethanol metabolism is reviewed. Non-alcohol dehydrogenase (ADH) dependent pathways contribute to in vivo ethanol metabolism, but the respective role of each has long been debated. The principal data supporting a role for catalase is an occasionally reported moderate depression of ethanol metabolism after aminotriazole. In deermice lacking ADH, we observed a slight (though not statistically significant) decrease in basal ethanol metabolism of hepatocytes after aminotriazole. However, this decrease was found to parallel a similar inhibition of MEOS by aminotriazole, and thus may not reflect catalase mediated peroxidation in this animal. 1-butanol, a competitive inhibitor of ethanol oxidation by MEOS and not a substrate for catalase, decreased ethanol metabolism by hepatocytes in a concentration dependent manner. These results, as well as those from other investigators, indicate that MEOS mediates virtually all of non-ADH ethanol metabolism in vivo.