The Effect of Chronic Ethanol Consumption on Enzyme Activities of the Energy-supplying Metabolism and the Alcohol-aldehyde Oxidizing System in Rat Hearts

We investigated in rat hearts if chronic alcohol consumption causes an enzymatic adaption of the energy-supplying metabolism and/or of the alcohol-aldehyde metabolizing system. 16 rats were pair-fed with a liquid diet for 10 weeks. Ethanol was added to this diet to amount for 35% of calories in eight rats and was isocalorically replaced by saccharose in the control group. Selected enzyme activities of the glycolysis, the glycogenolysis, the beta-oxidation of fatty acids, the citric acid cycle and the alcohol-aldehyde oxidizing system were determined in the supernatants of the homogenized hearts. The intracellular redox state was assessed by measurement of the myocardial nicotinamide coenzymes. Enzyme activities of the alcohol-aldehyde metabolizing system did not alter after chronic alcohol intake. As we found that the capacity to oxidize acetaldehyde was much higher than the ability to oxidize ethanol we must question the role of acetaldehyde in inducing alcoholic cardiomyopathy. Chronic ethanol treatment significantly increased the activity of glyceraldehyde-3-phosphate dehydrogenase and decreased the activity of glycogen phosphorylase. The impairment of the hydroxyacylCoA dehydrogenase was not significant. The other measured enzyme activities did not alter, nor the intracellular redox state. The enzymatic adaption indicates an impaired glycogenolysis, an increased glycolysis, and probably a diminished beta-oxidation of fatty acids. We expect that the measurement of the responding enzyme activities in human endomyocardial biopsies should be a good tool to further classify cardiomyopathies according to biochemical criteria.