Effect of ozone on erythrocyte membrane adenosine triphosphatase

Human erythrocyte membrane fragments were exposed to O3 over varying lengths of time. Ozone was found to have a deleterious effect on the ouabainsensitive ATPase (EC 3.6.1.3) in the membrane fragments. After 1 min of exposure to O3, which was generated at a rate of 4.0 mumol/min, ouabain-sensitive ATPase activity decreased to 26% of the control. Ouabain-insensitive ATPase was found to be unaffected by O3 exposure under the test conditions. Additions of ascorbic acid or cysteine, prior to O3 exposure, partially protected the enzyme from inactivation. However, the inactivating effect of O3 could not be reversed by addition of either ascorbic acid or cysteine after exposure. Superoxide dismutase or catalase did not afford significant protection. The enzyme could not be protected by Ellman's reagent. The inactivating effect of O3 on the ouabain-sensitive ATPase was also demonstrated in exposure of intact erythrocytes. No detectable change was observed in glycolytic activity in the hemolysate prepared from O3-treated erythrocytes, however. It was postulated that inactivation of the membrane ATPase by O3 may be responsible for the destructive effect of O3 on the red cell.