Ozone alteration of transport of cations and the [formula omitted]-ATPase in human erythrocytes

Abstract

The rates of movements of Na + and K + across the red cell membrane, controlled by active transport and sensitive to ouabain, were slightly decreased (15 to 20%) by exposure of the cells to high levels of ozone (14 μmol), in a manner suggesting inhibition of the transport Na + K + -ATPase. However, when measured in intact cells, the Na + K + -ATPase did not seem to be inhibited significantly by ozone. Neither the concentration of intracellular ATP nor the glucose transport to provide energy was significantly decreased by ozone treatment. Yet, the sensitivity to ouabain, as measured by the ability of the red blood cell ghost to bind ouabain, was reduced by exposure of the cell to ozone. Only when the Na + K + -ATPase activity was measured in broken or in Tris buffer-treated ghosts could a significant inhibition by ozone exposure be observed. Such evidence disputes recent proposals that a loss of transport ATPase activity results in the volume and shape changes known to occur in red cells in vivo after ozone exposures. We propose that the ozone exposure modifies the red blood cell membrane itself, rather than the Na + K + -ATPase. This membrane modification then causes the observed inhibition of the Na + and K + transport.