Reduction of 8-hydroxyguanine in human leukocyte DNA by physical exercise

We investigated the effect of physical exercise on the level of 8-hydroxygu anine (8-OH-Gua), a form of oxidative DNA damage, and its repair activity i n human peripheral leukocytes. Whole blood samples were collected by venipu ncture from 21 healthy male volunteers (10 trained athletes and 13 untraine d men), aged 19-50 years, both before and after physical exercise. Trained athletes showed a lower level of 8-OH-Gua (2.4 +/- 0.5/10(6) Gua, p = 0.003 2) before exercise when compared to that of untrained men (6.2 +/- 3.5). Th e mean levels of 8-OH-Gua of untrained subjects decreased significantly (p = 0.0057) from 6.2 +/- 3.5/10(6) Gua (mean +/- SD/10(6) Gua) to 3.3 +/- 1.4 /10(6) Gua after physical exercise. On the other hand, the mean levels of r epair activity of untrained subjects significantly increased after exercise (p = 0.0093) from 0.037 +/- 0.024 (mean DNA cleavage ratio +/- SD) to 0.05 6 +/- 0.036. In the trained athletes 8-OH-Gua level and its repair activity were not changed before and after the exercise. We also observed inter-ind ividual differences in 8-OH-Gua levels and its repair activities. These res ults suggest that physical exercise causes both rapid and long-range reduct ion of oxidative DNA damage in human leukocytes, with individually differen t efficiencies.