Oxidant levels/redox active iron release, and UCP3 levels in rat skeletal muscle. Rat skeletal muscle was stained with H2DCFDA to gain a rough estimate of relative steady-state oxidant levels and redox-active iron release levels [both of which can increase DCF fluorescence, (26)] in young control (YC), young exercised (YE), old control (OC), old exercised (OE), as depicted in A. Statistically significant differences were not observed. B: Western Blot analysis of UCP3 revealed significant decreases with age in both the sedentary and the exercise-trained groups. Values are expressed as means ± SD for six animals per group (*P < 0.05). All samples were run on the same gel; therefore, representative lanes were removed for final presentation.