title: Blood selenium and glutathione peroxidase activity of populations in New Zealand, Oregon, and South Dakota.
abstract: The relationship of whole blood selenium (Se) to glutathione peroxidase (GPX) activity was examined for individuals in New Zealand, Oregon, and South Dakota who represented, respectively, populations with exposure to low, medium, and high amounts of Se. The mean (respective) blood Se levels were 60, 200, and 400 ng/ml. Intergroup differences in blood Se levels were highly significant (P less than 0.001). GPX assays were performed using two variations of an enzyme-coupled procedure to assess the equivalence of the two methods. Despite a fourfold difference in absolute activities measured by these methods, the GPX activities were highly correlated (r = .86) between procedures. Average blood GPX activity was significantly lower (P less than 0.001) for the New Zealand group compared with the other two groups, but there was no difference in GPX activities between the Oregon and South Dakota groups. Linear regression of GPX vs. Se values within each group indicated a significant correlation of these parameters only in the New Zealand group (r = .46, P less than 0.01). Comparison of these parameters for combined data from all three groups also showed a significant positive correlation (r = .60, P less than 0.001). A saturation model (In GPX = k1 + k2 (Se)-1)) fits the combined data better (r = .80, P less than 0.01) than does direct comparison of the two parameters. These results suggest that GPX activity is an appropriate indicator of human Se status only in populations with below normal exposure to Se, as activity of this enzyme is saturated at relatively low levels.
authors.affiliation: Department of Agricultural Chemistry, Oregon State University, Corvallis 97330.
authors.forename: P D
authors.initials: PD
authors.lastname: Whanger
authors.forename: M A
authors.initials: MA
authors.lastname: Beilstein
authors.forename: C D
authors.initials: CD
authors.lastname: Thomson
authors.forename: M F
authors.initials: MF
authors.lastname: Robinson
authors.forename: M
authors.initials: M
authors.lastname: Howe
mesh_terms: D005979:Glutathione Peroxidase / Q000097:blood*; D006801:Humans; D009520:New Zealand; D009922:Oregon; D012016:Reference Values; D012044:Regression Analysis; D012643:Selenium / Q000097:blood*; D013023:South Dakota
chemical_list: D005979:Glutathione Peroxidase; D012643:Selenium