Effects of ozone on the activity of erythrocyte membrane Na(+)-K+ ATPase.

Ozone (5 mumol.min-1) inhibited the human erythrocyte membrane Na(+)-K+ ATPase (EC.3.6.1.39) activity in a time dependent manner. Inhibition was more pronounced for the first 5 min of ozone exposure in the directly ozone exposed membranes than in the membranes prepared from ozone exposed erythrocytes. However, Na(+)-K+ ATPase activities of both preparations were inhibited to the same extent (about 70%) at the end of 10 min ozone exposure. It was also determined that there was a close relationship between the decrease of enzyme activity and the increase in the thiobarbituric acid reactive substances in both types of preparations. Na(+)-K+ ATPase was inhibited by ozone even at the presence of vitamin E or vitamin C. However, the degree of the inhibitions and the amounts of thiobarbituric acid reactive products formed were smaller than the corresponding values found in the absence of these vitamins.