[Influence of thyroxine on lipid peroxidation in mitochondrial membranes]

In concentrations above 5.10(-7) M thyroxin brought about a delay in chemifluorescence development and decreased the slope of semilogarythmic plot of chemifluorescence curve at the initial step of the fluorescence slow flash. The antioxidant activity of thyroxin was found to be insignificantly lower than that of the well-known antioxidant alpha-tocopherol. In lower concentrations (about 1.10(-8) M) the hormone can act as prooxidant, the effect being the highest in the case of intact mitochondria incubated in the phosphate-containing medium in the presence of Mg2+ ions, and much less in the mitochondria treated in hypotonic medium containing Ca2+ ions.