Uptake and oxidation of acetaldehyde by intact human erythrocytes

Human erythrocytes were examined for acetaldehyde-oxidizing capacity of intact cells, in comparison with its uptake under various conditions. The oxidation was found to be predominant over other possible acetaldehyde-metabolizing pathways, particularly with low concentrations of acetaldehyde. Further investigation using three media which differed in the initial pyruvate level showed an independence of acetaldehyde oxidation rate up to the high cellular lactate/pyruvate concentration ratio. The apparent non-oxidative acetaldehyde uptake obtained by subtraction of oxidation from the total uptake, was reduced when pretreating the erythrocytes with pyridoxal but not with pyridoxal 5'-phosphate. Though N-ethylmaleimide also inhibited the non-oxidative uptake, another sulfhydryl blocking reagent, p-chloromercuribenzoate was without effect. Thus, in addition to the oxidation, acetaldehyde may be involved in a reaction such as binding to the red cell components, as the minor metabolizing pathway in the erythrocytes.