Selenium and glutathione peroxidase in human saliva and other human body fluids

Human body fluids such as mixed saliva, erythrocyte, plasma and mature breast milk were analysed for selenium (Se) and Se-dependent glutathione peroxidase (GSH-Px), which is the only active form of Se known in man. Selenium-dependent GSH-Px activity was detected for the first time in human mixed saliva. Body fluid GSH-Px, Se and protein contents expressed in terms of volume increased in the order, saliva less than milk less than plasma less than erythrocyte. However, the sequence of increase for GSH-Px (U/mg protein) and GSH-Px-bound Se (%) was plasma less than milk less than erythrocyte less than saliva, and that for Se (ng/mg protein) was erythrocyte less than saliva less than plasma less than milk. Significant positive correlations were found between GSH-Px and Se contents and between protein and Se contents expressed per volume for human saliva, erythrocyte and the whole human fluids investigated. Positive correlations between erythrocyte and plasma Se (ng/mg protein) and between plasma and saliva GSH-Px-bound Se (%) were also significant.