ENDOTHELIUM-DERIVED OXIDATIVE STRESS MAY CONTRIBUTE TO EXERCISE-INDUCED MUSCLE DAMAGE

In exercise-induced muscle damage, oxidative stress derived from the l iberation of reactive oxygen species (ROS) is assumed to be of etiolog ical importance. Xanthine oxidase (XO) located in capillary endotheliu m is one of the possible sources for ROS, mainly investigated so far u nder conditions of ischemia/reperfusion. XO can be inhibited by allopu rinol. To investigate the contribution of XO for the oxidative stress- induced development of muscle damage, mice were subjected to a single bout of exhaustive running exercise. Another exercised group received allopurinol. The reduced form of glutathione (GSH) was measured to est imate the amount of oxidative stress in soleus muscle, and the same mu scle was examined in the light and electron microscope at different pe riods of time (0, 48, 96 h) after exercise. While exercise alone resul ted in a marked reduction of GSH indicative for oxidative stress, whic h only recovered at 96 h, the administration of allopurinal to exercis ed animals induced a complete recovery already at 48 h after exercise. Muscle damage was more pronounced in the exercised animals which had not been treated with allopurinol. It is concluded that endothelium-de rived ROS contribute reasonably to oxidative stress to exercised muscl e and to fiber and capillary damage.