Nitrogen Dioxide and the Erythrocyte Redox State

Abstract

• Normal human erythrocytes were exposed for two hours at 38 C to an atmosphere of air containing variable concentrations of nitrogen dioxide, in order to detect any primary cytoplasmic effect of NO₂ on the calculated oxidation-reduction (redox) ratio ([NAD⁺]/[NADH]) of a mitochondria-free cell. Substantial increases in the redox ratio were noted only when NO₂ concentrations exceeded 15 ppm. In the range of 15 to 500 ppm NO₂, the increase in the redox ratio significantly correlated with the NO₂ concentration (r=.71; P<.01). Intracellular to extracellular anion distribution ratios for chloride, lactate, and pyruvate were similar in NO.₂ and nonNO₂ exposed cells, suggesting absence of a substantial hemolytic effect.

These data identify a direct cytoplasmic NO₂-induced biochemical change that may be mediated by a mechanism other than lipid peroxidation. Alteration of hemoglobin or NAD-NADH-dependent enzyme activity is suggested.