STUDIES OF THE OXIDATION OF ETHANOL TO ACETALDEHYDE BY OXYHEMOGLOBIN USING FLUORIGENIC HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

We noted a rise in acetaldehyde levels in clinical samples of venous w hole blood containing ethanol that did not occur in samples from teeto talers. Experiments were performed to define the mechanism involved in acetaldehyde production. The addition of 0.10% ethanol to whole blood produced an immediate increase in acetaldehyde due to acetaldehyde in the stock solution followed by a subsequent increase that became stat istically significant by 48 hr. Separation of blood into components do cumented that the increase in acetaldehyde was associated with the red cell but not plasma fraction. Incubation of isolated hemoglobin with ethanol produced a rise in acetaldehyde levels. Incubation of oxygenat ed whole blood with ethanol produced a linear increase in aceteldehyde , whereas nitrogen-exposed blood produced no increase. The rise of ace taldehyde in the presence of ethanol was dependent on the concentratio n of oxygenated hemoglobin A(0). Addition of inhibitors of catalase, a lcohol dehydrogenase, and glycolytic enzymes (aminotriazole, azide, py razole, sodium fluoride, sodium citrate, and iodoacetate) did not inhi bit the rise of acetaldehyde, but addition of the hemoglobin ligand cy anide abolished the rise in acetaldehyde. Kinetic analysis with oxygen ated whole blood plus inhibitors revealed a K-m of 2.5 mm and V-max of 1.42 mu M/min. We conclude that oxyhemoglobin contributes to the meta bolism of ethanol to acetaldehyde. These findings may explain in part the high levels of acetaldehyde found in red cells compared with plasm a. The results also have implications for the optimum storage of blood samples for acetaldehyde analysis.