Altered oxidative stress in healthy old subjects.

To understand the magnitude of oxidative phenomena during senescence, we evaluated, as antioxidant, the activity of glutathione peroxidase (GSH-Px) in erythrocytes and plasma uric acid (UA) levels together with the malondialdehyde (MDA) levels in plasma, as an index of lipid peroxidation, in 46 apparently healthy elderly subjects (87±6 years old; mean±SD), and 49 young subjects (29±4 years old). The elderly subjects had lower erythrocyte GSH-Px activity (15.7±4.8 vs 20.2±7.0 U/g Hb, p<O.001; mean±SD) and plasma UA levels (192±46 vs 240±54 mmol/L, p<0.001); but higher MDA levels (5.3±0.8 vs 4.1±0.8 mmol/L, p<0.001) than the young subjects. Of additional in terest was the finding of a positive correlation between age and erythrocyte GSH-Px activity (r=0.74, p<0.001), and a negative correlation between age and plasma MDA levels (r=-0.83, p<0.001) in the elderly group. Although erythrocyte GSH-Px activity was significantly less in the elderly than in the young group, the oldest subjects showed the greatest erythrocyte GSH-Px activity and had lower MDA levels.