BIOLOGICAL VARIABILITY OF SUPEROXIDE-DISMUTASE, GLUTATHIONE-PEROXIDASE, AND CATALASE IN BLOOD

We studied the biological variability of blood superoxide dismutase (SOD; EC 1.15.1.1), glutathione peroxidase (GPX; EC 1.11.1.9), and catalase (CAT; EC 1.11.1.6) in a sample of 1836 apparently healthy subjects, ages 4-97 years. SOD and GPX activities were assayed in plasma (P) and erythrocytes (E) by automated methods, and CAT was measured in erythrocytes by a manual technique. No statistically significant variation of these antioxidant enzyme activities according to gender was demonstrated, except for E-GPX, which was slightly but significantly higher in women than in men (P < 0.001). Activities appear rather stable in adults < 65 years old, but decrease for most enzymes in the elderly. There is no evidence that weight, blood pressure, or menopause influences the antioxidant enzymes' activities. In girls ages 10-14 years, E-SOD activity is reduced by 16% (P < 0.05) after menarche. Variations related to smoking and alcohol consumption are slight and concern only P-SOD and P-GPX, respectively. Conversely, intake of some drugs (e.g., anti-inflammatory agents, antidepressants, and thyroid hormones) modifies activity of some of the three enzymes. E-SOD positively correlates with P-SOD (r = 0.216, P < 0.001) and E-CAT (r = 0.123, P < 0.001), and E-GPX with P-GPX (r = 0.218, P < 0.001). Finally, we propose reference intervals for activities of the three antioxidant enzymes in blood in individuals < 65 years old.