Altered Glutathione Levels in Ischemic and Postischemic Skeletal Muscle: Difference between Severe and Moderate Ischemic Insult

The purpose of the present study was to investigate how the duration of ischemia and reperfusion affect the glutathione (GSH) levels in skeletal muscle and to assess the presence of oxidative stress by quantitating oxidized glutathione (GSSG) and the ratio of GSSG/GSH. The amounts of GSH and GSSG were quantitated in the tibialis anterior muscle of the rat hind limb after 2 and 4 hours of tourniquet ischemia and after 1 and 5 hours of reperfusion, and the levels were compared to those in nonischemic control tibialis anterior muscles. In muscles subjected to 2 hours of ischemia, the levels of GSH, GSSG, and the ratio GSSG/GSH did not differ significantly from those of nonischemic controls. After 4 hours of ischemia without reperfusion, the GSH levels were slightly increased, compared to controls (p < 0.05). After 1 hour of reperfusion following 4 hours of ischemia, the levels of GSH decreased by 50% compared to control (p < 0.01), and still after 5 hours of reperfusion the levels of GSH were 50% lower than control levels. The GSSG/GSH ratio did not change during 1 and 5 hours of reperfusion compared to control. A major finding in this study was that, during reperfusion after severe ischemia of 4 hours, there was a marked depletion of glutathione, which was not seen after a moderate ischemic insult of 2 hours.