Hepatic aldehyde dehydrogenase (E.C. 1.2.1.3.) isoenzymes and malondialdehyde levels in alcoholic liver disease.

: To clarify the controversially discussed behaviour of hepatic ALDH isozymes in different liver diseases, 98 liver biopsy specimens were investigated as to their total ALDH and their isozyme activity. Simultaneously the malondialdehyde (MDA) content was measured in both biopsy samples and serum. The results show a significant decrease of the "low Km" isozyme E-2 activity depending on the severity of the liver disease. The tendency for the E-2 activity to decrease was greater in alcoholic than in nonalcoholic liver diseases. Although in all our diagnosis groups elevated MDA concentrations could be measured in both serum and liver tissue, a direct specific inhibitory effect on the E-2 activity could not be confirmed. The change from the low Km pathway to the high Km pathway of aldehyde detoxification, however, may contribute to the progress in alcoholic liver disease.