Effects of nitrogen dioxide on red blood cells of rats: alterations of cell membrane components and populational changes of red blood cells during in vivo exposure to NO2.
Male Wistar rats were exposed to 4 ppm NO2 for 10 days in order to examine the relationship between the changes in components of red cell membranes and alterations of erythrocyte population. Na+, K+-ATPase activity of red blood cell membranes of exposed animals showed a significantly higher value than that of the control at the first and fourth days of exposure and then decreased to under the control value at the seventh day. In order to examine changes in erythrocyte population, red blood cells were fractionated into four fractions according to their density using Dextran density centrifugation. The alteration of the percentage of lowest-density cells (fraction IV) of exposed animals was completely consistent with that of Na+,K+-ATPase activity in addition to that of the sialic acid content as described in a previous report (K. Kaya, T. Miura, and K. Kubota (1980). Environ. Res. 23, 397-409.). The percentage of fraction IV was 1.43- (P less than 0.05) and 1.68-fold (P less than 0.01) those of the control at the first and fourth days of exposure, respectively, and then decreased to under the control value at the seventh day. This decrease accompanied increases in the percentages of higher-density cells (fractions I and II). Examination of subfractions of red blood cells showed that Na+,K+-ATPase activity and the sialic acid content of three fractions with lower densities have higher values in exposed animals than in the control 1 day after exposure to NO2. Based on these results, it is concluded that increases in Na+,K+-ATPase activity and the sialic acid content occurring 1 day after exposure to 4 ppm NO2 were caused by elevated levels of these components in three fractions with lower densities as well as by an increase in the percentage of lowest-density cells in the erythrocyte population. It was also suggested that NO2 inhalation accelerated aging of erythrocytes with respect to density. The change in Ca2+,Mg2+-ATPase activity, in addition to that in the hexose content as described in a previous report (Kaya et al., 1980), was different from those in the sialic acid content and Na+,K+-ATPase activity. Ca2+,Mg2+-ATPase activity and the hexose content of exposed animals showed slightly reduced values 1 day after exposure to NO2. In all subfractions of red blood cells these values were slightly lower in exposed animals than in the controls. Therefore, reduction in Ca2+,Mg2+-ATPase activity and the hexose content is not due to changes in erythrocyte population.
D000818:Animals; D001273:Atmosphere Exposure Chambers; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects* / Q000201:enzymology; D006601:Hexoses / Q000032:analysis; D008297:Male; D019158:N-Acetylneuraminic Acid; D009585:Nitrogen Dioxide / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012794:Sialic Acids / Q000032:analysis; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D006601:Hexoses; D012794:Sialic Acids; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D019158:N-Acetylneuraminic Acid; D009585:Nitrogen Dioxide