Formation of the 37KD liver protein-acetaldehyde adduct in vivo and in vitro.

A liver protein with molecular weight of 37,000 can form adducts with acetaldehyde in vivo when rats are fed alcohol chronically. This 37KD protein is not directly involved in the hepatic metabolism of ethanol but it requires alcohol dehydrogenase activity to form adducts with acetaldehyde. The 37KD protein-AA is located in cytosol of the liver. However, under certain circumstances e.g. when fed an alcohol-containing liquid diet supplemented with cyanamide (an aldehyde dehydrogenase inhibitor that raises blood acetaldehyde concentrations), this 37KD protein-acetaldehyde adduct (protein-AA) becomes incorporated into liver plasma membranes. The same 37KD protein-AA can also form in vitro with cultured rat hepatocytes treated with ethanol. The formation of the 37KD protein-AA in the cultured liver cells increased with time and was dependent on concentrations of ethanol in the culture medium. Thus, protein-AAs can form in vivo and in liver cell culture upon chronic alcohol exposure, and a 37KD protein in liver is highly susceptible to chemical modification by acetaldehyde.