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

Single-dose ethanol administration to rats caused inhibition of liver mitochondrial monoamine oxidases (MAO) A and B, and an increase in sus ceptibility of MAO A (but not MAO B) to limited proteolysis. Chronic e thanol feeding resulted in a less distinct alteration in catalytic act ivity and susceptibility to proteolysis of mitochondrial MAO, but incr eased the amount of soluble MAO. The sensitivity of membrane-bound MAO to inhibitors (imipramine and chlorpromazine), action of which depend s on their lipophilicity and/or hydrophobicity, remained unchanged, co mpared with controls. Increased amounts of soluble MAO seen after chro nic ethanol feeding probably reflect an impairment of insertion of new ly synthesized enzyme molecules into the outer mitochondrial membrane, rather than solubilization of MAO from it.