Responses of antioxidant system to acute and trained exercise in rat heart subcellular fractions.

The effects of acute and trained exercise on antioxidant enzymes (AOE), glutathione (GSH), and malondialdehyde (MDA) were compared in rat heart subcellular fractions and red blood cells. Fischer-344 rats were exercised acutely to 100% VO2 max and another group of Fischer-344 rats were given trained exercise for 10 weeks. The AOE and MDA were measured by spectrophotometry and GSH and oxidized GSH (GSSG) by high pressure liquid chromatography. Trained exercise significantly increased cytosol GSH to 131% of sedentary control (SC). Acute exercise significantly increased mitochondrial superoxide dismutase, catalase, and glutathione peroxidase by 167%, 358%, and 129% of SC, respectively, whereas enzyme activities following trained exercise were increased by 133%, 166%, and 128% of SC. The mitochondria/cytosolic ratio for superoxide dismutase, catalase, and glutathione peroxidase after acute exercise increased to 1.9, 2.7, and 1.7, respectively, whereas the respective ratios of these enzymes after trained exercise were 1.3, 1.6, and 1.3. Acute exercise contributed to oxidative stress more than trained exercise. Acute exercise resulted in a larger increase in enzyme activities than trained exercise, possibly as a compensatory mechanism to cope with the enhanced production of superoxides and oxyradicals during exhaustive exercise.