Does the platelet-activating factor affect the antioxidant defense system?The possible role of hyperbaric oxygenation

The platelet-activating factor (PAF) is an inflammatory mediator and it may exert some of its effects by reactive oxygen species (ROS). We investigate d the effects of PAF and hyperbaric oxygenation (HBO) on copper (Cu) and zi nc (Zn) levels in plasma and the intracellular antioxidant enzyme activitie s of rats. PAF administiration caused a decrease in erythrocyte catalase (C AT) and glutathione peroxidase (GPx) activities and in the plasma zinc leve l. Following PAF administration, exposure to HBO also caused a decrease in erythrocyte GPx activity. These results support the hypothesis that PAF may produce free oxygen radicals and HBO enhances this effect, The enzyme acti vities of the antioxidant defense system were found to be affected by these oxidative processes. This is likely to be the result of excessive producti on of ROS or overutilization and/or inhibition of the antioxidant enzymes.