Oxygen radical generation of neutrophils: a reason for oxidative stress during marathon running?

Hematological parameters and blood markers that indicate oxidative stress, such as lipid peroxides (LPO), reduced and oxidized glutathione (GSH, GSSG), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), were measured in 18 marathon runners before, immediately after the race, and after 8 days of rest. In parallel, the oxygen radical generation of neutrophils (PMN) was measured by chemiluminescence in six randomly selected runners. After the race, a 4.4-fold enhanced PMN count and a 1.4-fold increased capacity to generate oxygen radicals of the PMN (2.20+/-0.38 vs. 3.12+/-0.69 arb. unit/10(6) cells) were found. Consequently, a 6.25-fold increased capacity to generate oxygen radicals of the post-run blood (7.26+/-1.3 vs. 45.40+/-10.3 arb. unit/ml blood) was calculated. This points to PMN as an important oxygen radical source established in the runners' blood, which could contribute to the oxidative stress indicated in the post-run blood by increased LPO (11.46+/-3.09 vs. 13.09+/-3.14 micromol/l plasma), GSSG (0.038+/-0.003 vs. 0.045+/-0. 005 mmol/l blood) and GSSG/GSH ratio (3.8+/-0.5 vs. 4.1+/-0.6%) and by decreased SOD (15.63+/-1.78 vs. 14.58+/-1.51 10(3)U/mmol Hb) and GSH-Px (485.1+/-107.1 vs. 434.9+/-101.7 U/mmol Hb). Despite the decline of the oxygen radical source during rest, the oxidative stress in the blood did not decrease in all runners.