Physical exercise intensity can be related to plasma glutathione levels

The aim of the present study was to examine the effect of different kinds o f physical exercise on plasma glutathione levels. Male Wistar rats were ran domly divided into four groups: In walking group (W; n=6), rats were traine d to walk 0.8 m/min for 45 min; slow running group (SR; n=6) were trained t o run 4 m/min for 45 min; fast running group (FR; n=6) ran 8m/min for 60 mi n and control rats (C; n=6) remained in their home cages. All animals were sacrificed after exercise and the levels of reduced glutathione (GSH) in pl asma samples determined by high performance liquid chromatography (HPLC) wi th a fluorescent detector. Compared to controls, exercise did not change GS H plasma levels of the W group. A tendency to decrease blood GSH was observ ed in plasma samples of the SR group and in the FR group, physical exercise resulted in a dramatic decrease in GSH plasma levels. These data suggest t hat during light physical exercise there is a low production of reactive ox ygen species (ROS) with a low request for antioxidant defence such as oxida tion of GSH. The dramatic decrease observed in GSH levels in FR rats would indicate the presence of oxidative stress able to modify blood antioxidant profiles. Our results suggest that GSH plays a central antioxidant role in blood during intensive physical exercise and that its modifications are clo sely related to exercise intensity.