FORMATION OF THE 37-KD PROTEIN-ACETALDEHYDE ADDUCT IN PRIMARY CULTURED RAT HEPATOCYTES EXPOSED TO ALCOHOL

We have previously reported that a 37‐kD liver protein formed an adduct with acetaldehyde in vivo when rats were fed alcohol chronically. To understand the mechanism of the formation of this proteinacta ldehyde adduct, rat hepatocytes in primary culture were treated with ethanol in vitro for several days. When cultured in hormone‐enriched and trac metalenriched Waymouth's medium, alcohol dehydrogenase activities in hepatocytes decreased only about 30% during 6 days of culture. At the end of the specified time, protein extracts of hepatocytes were immunotransbloted with rabbit immunoglobulin G that recognized acetaldehyde adduct as an epitope. The 37‐kD protein, acetaldehyde adduct band could be detected within 3 days in cells that had been treated with alcohol at a steady‐state concentration as low as 5 mmol/L. Although the maximal intensity was obtained at approximately 10 to 40 mmol/L ethanol, addition of cyanamide (an inhibitor of aldehyde dehydrogenase) further increased the intensity of this protein‐acetaldehyde adduct band by more than twofold. A good correlation existed between acetaldehyde concentration in the medium and the intensity of the 37‐kD protein acetaldehyde adduct band. Formation of the 37‐kD liver protein‐acetaldehyde adduct is thus dependent on acetaldehyde, and the 37‐kD protein is apparently unusually susceptible to chemical modification by acetaldehyde.(HEPATOLOGY 1990;11:401–407.) Copyright © 1990 American Association for the Study of Liver Diseases