Hellsten Y, Svensson M, Sjödin B, Smith S, Christensen A, Richter E A, Bangsbo J
Copenhagen Muscle Research Centre, August Krogh Institute, University of Copenhagen, Copenhagen, Denmark.
Free Radic Biol Med. 2001 Dec 1;31(11):1313-22. doi: 10.1016/s0891-5849(01)00631-1.
Seven males performed two exhaustive cycling bouts (EX1 and EX2) at a work-rate of 90% of maximal oxygen uptake, separated by 60 min. During EX1 there was a significant accumulation of urate (from 0.16 +/- 0.02 to 0.27 +/- 0.03 micromol/kg d.w.) and allantoin (from 0.39 +/- 0.05 to 0.69 +/- 0.14 micromol/kg d.w.) in the muscle. An uptake of urate was observed in early recovery from EX1 (0-9 min: 486 +/- 136 micromol; p <.05). There was no exchange of total glutathione or cysteine over the muscle either during or after exercise, and muscle and plasma total glutathione remained unaltered (p <.05). The glycogen levels were lowered by 40% at the onset of EX2, yet the level of oxidative stress in EX1 and EX2 was similar as evidenced by a similar increase in muscle allantoin in both exercise bouts. The data suggest that urate is utilized as antioxidant in human skeletal muscle and that reactive oxygen species are formed in muscle during intense submaximal exercise. No net exchange of glutathione appears to occur over the muscle either at rest, during exercise or in recovery. Moreover, when an exhaustive exercise bout is repeated with lowered glycogen levels, the level of oxidative stress is not different than that of the first bout.
七名男性以最大摄氧量的90%的工作强度进行了两次力竭性骑行运动（EX1和EX2），两次运动间隔60分钟。在EX1期间，肌肉中的尿酸盐（从0.16±0.02微摩尔/千克干重增加到0.27±0.03微摩尔/千克干重）和尿囊素（从0.39±0.05微摩尔/千克干重增加到0.69±0.14微摩尔/千克干重）显著积累。在EX1后的早期恢复阶段（0 - 9分钟：486±136微摩尔；p <.05）观察到尿酸盐的摄取。在运动期间或运动后，肌肉中总谷胱甘肽或半胱氨酸均未发生交换，肌肉和血浆中的总谷胱甘肽保持不变（p <.05）。在EX2开始时糖原水平降低了40%，然而EX1和EX2中的氧化应激水平相似，这在两次运动中肌肉尿囊素的类似增加中得到了证明。数据表明，尿酸盐在人体骨骼肌中被用作抗氧化剂，并且在高强度亚极量运动期间肌肉中会形成活性氧。在休息、运动期间或恢复过程中，肌肉中似乎都没有谷胱甘肽的净交换。此外，当在糖原水平降低的情况下重复进行力竭性运动时，氧化应激水平与第一次运动时没有差异。
