The selenium-dependent antioxidative system

The selenium containing glutathione peroxidase protects the organism agains t hydrogen and organic peroxides. In order to establish reference values, 9 9 healthy blood donors (age: 37.2 +/- 11.6 years, 46 male and 53 female, am ong them 26 never drinking alcohol and 79 non-smokers) were included in the study. Free and bound malondialdehyde (MDA) were determined using thiobarb ituric acid, glutathione peroxidase (GSH-Px) in plasma and erythrocytes by kinetic: photometric reaction, and selenium (Se) by ETAAS. The concentratio ns or activities (mean +/- 2 SD) were for free MDA: 0.27 +/- 0.14 mu mol/l, bound MDA,: 1.10 +/- 0.48 mu mol/l, GSH-Px in plasma: 131 +/- 38 U/l, GSH- Px in erythrocytes: 20.4 +/- 9.8 U/mg Hb, Se in plasma: 0.84 +/- 0.20 mu mo l/l, Se in erythrocytes: 0.093 +/- 0.032 mmol/10(12) cells, and Se in whole blood: 0.97 +/- 0.24 mu mol/l. No correlations have been found between the se parameters and age or smoking. Male persons had higher bound MDA than fe male (1.21 +/- 0.21 versus 1.02 +/- 0.25, p<0.001). The consumption of alco hol led to higher Se in plasma (0.86 +/- 0.10 mu mol/l versus 0.80 +/- 0.09 mu mol/l, p=0.003). increasing hematocrit, body mass index and higher numb ers of erythrocytes were observed together with a linear increase in bound MDA, and a decrease in plasma GSH-Px. Further correlations have been found between GSH-Px in plasma and Se in plasma (p<0.001, r=0.33) or free MDA (p= 0.02, r=0.24, all parameters referring to one liter whole blood). There is a distinct correlation between the activity of plasma GSH-Px and free MDA c oncentrations in contrast to bound Malondialdehyd concentrations. It seems that a healthy organism is able to enlarge the capacity of the selenium-dep endent antioxidative system bender increasing oxidative stress.