EXERCISE-INDUCED DNA EFFECTS IN HUMAN-LEUKOCYTES ARE NOT ACCOMPANIED BY INCREASED FORMATION OF 8-HYDROXY-2'-DEOXYGUANOSINE OR INDUCTION OF MICRONUCLEI

The present study examined the effects of a short-distance triathlon o n the induction of DNA effects in peripheral leukocytes, urinary excre tion of oxidized DNA bases, and frequency of micronuclei in lymphocyte s of human volunteers. Induction of DNA effects was measured as increa sed DNA migration using the alkaline comet assay. Increased DNA migrat ion was found in leukocytes of all individuals at different time point s after exercise and revealed a biphasic pattern. Twenty-four hours po stexercise, elevated DNA migration was found, whereas lower values wer e detected 48 h after exercise. Seventy-two hours postexercise, the ma ximum increase in DNA migration was found and baseline values were sti ll elevated after 120 h. A modified protocol of the comet assay for th e detection of oxidized DNA bases revealed no differences in leukocyte s before and directly after the triathlon. Urinary excretion of 8-hydr oxy-2'-deoxyguanosine remained unaltered during the 5 consecutive days sampled. No differences were found in the micronucleus-frequency in l ymphocytes before or 48 and 96 h after exercise. Our data suggest that DNA effects detected with the comet assay in leukocytes of humans aft er exercise are secondary effects that do not originate from oxidized DNA bases and do not result in chromosome damage. (C) 1998 Elsevier Sc ience Inc.