Biochemical changes in rat erythrocytes caused by ethylene oxide exposure

When Wistar male rats were exposed to ethylene oxide (EtO) at a concentration of about 500 ppm, 6 hr a day, 3 days a week for 2, 6, or 13 weeks, hematological examination showed macrocytic, normochromic anemia with a high reticulocyte count. This result raised the possibility that the hemolytic process was responsible for the anemia. Thus, the following possible causes of hemolysis were investigated with erythrocytes obtained from control and EtO-exposed rats. (1) Metabolism in erythrocytes; (a) Hexose monophosphate cycle: The activity of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, or glutathione peroxidase was not affected, but the activity of glutathione reductase (GR) significantly decreased and did not recover by the addition of flavin adenine dinucleotide. Reduced glutathione content also decreased and the glutathione stability test was positive. (b) Embden-Meyerhof pathway: Adenosine triphosphate content did not decrease. (c) Lapoport-Luebering cycle: 2,3-Diphosphoglycerate content was not affected. (2) Membrane alterations: Osmotic fragility was not affected and the activity of acetylcholine esterase in the ghost membranes of the exposed group increased. (3) Hemoglobin stability: The heat test and the isopropanol test were negative. GR has an important function in maintaining the reducing power in erythrocytes, and the decrease in the activity caused by EtO induced an alteration of the glutathione stability. Although the mechanism of EtO-induced anemia could not be clearly explained, the inhibition of GR activity might be related to the anemia.