, 2004). Analyses were performed in liver, kidney, heart and brain S1 samples according to the method described previously (Pérez-Severiano et al., 2004). Aliquots of 200 μL of liver, kidney, heart and brain S1 were added to color reaction. TBARS levels were measured at 532 nm using a standard curve of MDA

and corrected by the protein content (Ohkawa et al., 1979). The CAT enzyme activity was determined in liver, kidney and heart S1 according to the method proposed by Aebi H (Aebi, 1984). Briefly, S1 aliquot (50 μL) was added to a medium containing potassium phosphate buffer (50 mM; pH 7.4) and H2O2 (1 mM). The kinetic analysis of CAT was started after H2O2 addition and the color reaction was measured at 240 nm. One unit of the enzyme is considered as the amount which decomposes 1 μmol H2O2/min at pH 7. The cerebral PD332991 Na+/K+ATPase enzyme activity was determined in brain S1 samples according to the selleck screening library method proposed by Muszbek et al. (1977), with some modifications. Briefly, the aliquots of skeletal muscle S1 (20 μL) were added to a reaction medium containing NaCl (115 mM), MgCl2 (2.5 mM), KCl (18 mM) and Tris–HCl buffer (45 mM and pH 7.4), with or without the Na+/K+ ATPase enzyme inhibitor ouabaine (5 μM). The method for ATPase activity measurement was based on the determination of the inorganic

phosphate (Pi) released to the reaction medium by the hydrolysis of the ATP according to the method proposed by Atkinson A (Atkinson et al., 1973). The reaction was initiated with the addition of the substrate ATP (1.5 mM) to the reaction medium and was finished by the addition of the color reagent (1 mL) containing ammonium molibdate (2%), Triton-X 100 (5%) and H2SO4 1.8 M (10%) after 15 min of incubation at 37 °C. The formed molibdate–Pi almost complexes

were measured spectrophotometrically at 405 nm. Values were calculated in relation to a standard curve constructed with Pi at known concentrations and corrected by the protein content. The enzyme was assayed as described previously (Sassa, 1982) by measuring the rate of product porphobilinogen (PBG) formation. After 10 min of pre-incubation with homogenized liver or total blood from treated mice at 37 °C, in a medium containing 100 mM potassium phosphate buffer, pH 6.8, the enzymatic reaction was initiated by adding the substrate aminolevulinic acid (ALA) to a final concentration of 2.5 mM. The incubation was carried out for 1 h, at 37 °C, and was stopped by adding 10% TCA containing 10 mM HgCl2. The reaction product was determined using a modified Ehrlich’s reagent at 555 nm, with a molar absorption coefficient of 6.1 × 104 for the Ehrlich porphobilinogen salt. The enzyme activity was expressed in percent of the control. GPx was determined as described previously (Paglia and Valentine, 1967).