SUMMARY

Experimental data have demonstrated that impaired antioxidant capacity is associated with increased levels of reactive oxygen species (ROS) production. ROS can cause inactivation of critical enzymes and induce denaturation that renders proteins nonfunctional. Total blood is continuously exposed to oxidative stress. The aim of the current study was to investigate the reduction of nitroblue tetrazolium (NBT) by the total blood in persons with periodontitis and aged subjects. Materials and methods. The reduction of NBT in the total blood was measured according to a previously described procedure (Demehin et al., 2001), with modifications. Eight mL of venous blood were taken by venipuncture in the morning before meals and in portions of 2 mL placed into 4 plastic test tubes. Blood clotting was controlled with heparin (20 units/mL). Then the test tubes with blood were placed in the thermostat at the temperature of 37°C and kept for 5 min. Next, NBT, the final concentration of which ranged to 1´10-4, was added to the blood in the test tubes, which were kept for 20 min at the temperature of 37°C. On completion of incubation, the tubes were centrifuged for 5 min at 2000´g to sediment any cells. The supernatant was decanted into fresh test tubes, and the absorbance of NBT in the samples was measured spectrophotometrically at wave length of 570 nm at 25°C