The purpose of this study was to investigate the effect of repeated exercise on oxidative damage to DNA in 10 well trained long distance runners who participated in an 8-day training camp. The average running distance during the camp was 30 +/- 3 km/day. The amount of urinary 8-hydroxy-deoxyguanosine (8-OHdG) excretion was used to estimate the oxidative DNA damage. Urine samples were collected for both a 3-day control period as well as throughout the camp. Blood samples were drawn after overnight fasting both before and after the camp. Urinary 8-OHdG excretion was significantly increased during the camp compared to the control period (265.7 +/- 75.5 vs. 335.6 +/- 107.4 pmol/kg/day, P < 0.05). The content of 8-OHdG in the lymphocyte DNA on the day after finishing the camp did not differ from that before the camp. Plasma TBARS, LDH, CK, CK-MB, and myoglobin significantly rose after the camp (P < 0.05). The plasma beta-carotene levels tended to rise after the camp, while the plasma alpha-tocopherol levels increased significantly after the camp (P < 0.05). These results indicate that repeated exercise augments oxidative stress and the DNA is also injured by exercise-induced reactive oxygen species. However, the oxidative damage to DNA is not accumulated by consecutive exercise, although it is sustained as long as the exercise is repeated.

No abstract

Young barley leaf is consumed as a popular green-colored drink, which is named “Aojiru” in Japan. In the present study, we examined effects of young barley leaf powder (BL) on gastrointestinal transit time (GTT) and fecal moisture and weight in comparison with wheat bran (WB) in male Sprague-Dawley rats. In addition, an attempt was made to identify BL components responsible for these effects by using various fractions of BL. Additionally, we examined the water-holding capacity and setting volume of BL in vitro. We also examined the granular structures of BL with a scanning electron microscope. As a result, BL supplementation in the diet increased the fecal weight and shortened GTT. Our results demonstrate that the active component responsible for the effect on increasing the fecal volume in BL is the water-insoluble dietary fiber fraction and that this effect is thought to be caused by stimulation of the gut tract by the pH lowering. Furthermore, the high laxative action of BL was thought to be ascribable to the high water-holding capacity due to the complicated structures of BL.

We investigated the effect of a single bout of intensive exercise on the excretion of 8-hydroxydeoxyguanosine in the 24 h urine from healthy non-smokers. We studied three exercise tests in Experiment 1; which consisted of incremental exercise to exhaustion on a treadmill in eleven male long distance runners. Experiment 2; which comprised incremental exercise until reaching exhaustion on abicycle ergometer in six male untrained subjects. Experiment 3; which consisted of a 20 km run by eleven male long distance runners. No differences in the urinary 8-hydroxydeoxyguanosine excretion were obselwed from days 1 or 3 after each respective exercise regimen.However, significant increases in the plasma creatine kinase activity were observed at 24 h or 48 h after exercise, except for Experiment 2. Our results thus suggest that the oxidative stress during a single bout of intensive exercise does not result in an accumulation of oxidative DNA damage.

The purpose of this study was to investigate the effect of endurance exercise on both the tissue and lymphocyte 8-hydroxy-deoxyguanosine (8-OHdG) content. Six dogs ran on a treadmill for 7 hours. Another six dogs were assigned to a sedentary control group. The exercised dogs were sacrificed immediately after exercise and the counterpart of the sedentary group was also sacrificed at the same time. The brain, lung, liver, spleen, kidney, jejunum, colon, diaphragm, heart, splenius muscle, and the medial and lateral portion of gastrocnemius muscle samples were then collected. Lymphocytes were sampled before and after exercise in the exercised dogs. The 8-OHdG content of lymphocyte DNA was found to significantly decrease after exercise (0.57 +/- 0.19 vs 0.33 +/- 0.10/deoxyguanosine (dG) x 10(5), P < 0.05). The colon was the only tissue which showed a significant decrease in the content (0.83 +/- 0.24 vs 0.54 +/- 0.15/dG x 10(5), P < 0.05). No tissue except for the colon showed any significant changes after exercise. These results therefore indicate that, immediately after endurance exercise, an augmented repair mechanism might thus play a role in the decrease of 8-OHdG in the lymphocytes and the colon, while the 8-OHdG generation might be counterbalanced by its repair in other tissues.