INFLUENCE OF ETHANOL ADMINISTRATION ON THE ACTIVITY AND COMPARTMENTATION OF RAT LIVER MONOAMINE OXIDASES

Single-dose ethanol administration to rats caused inhibitionof liver mitochondrial monoamine oxidases (MAO) A and B, andan increase in susceptibility of MAO A (but not MAO B) to limitedproteolysis. Chronic ethanol feeding resulted in a less distinctalteration in catalytic activity and susceptibility to proteolysisof mitochondrial MAO, but increased the amount of soluble MAO.The sensitivity of membrane-bound MAO to inhibitors (imipramineand chlorpromazine), action of which depends on their lipophilicityand/or hydrophobicity, remained unchanged, compared with controls.Increased amounts of soluble MAO seen after chronic ethanolfeeding probably reflect an impairment of insertion of newlysynthesized enzyme molecules into the outer mitochondrial membrane,rather than solubilization of MAO from it.