The influence of dietary history on the production of free radicals in rat liver microsomes.

Free radicals have been trapped in microsomal fractions from rat livers by the use of alpha-(4-pyridyl-l-oxide)-N-tert-butylnitrone (4-POBN) and detected by ESR spectroscopy. Using this technique we have investigated the effects of low dietary concentrations of vitamin E and selenium (Se) on free radical production. When the microsomal fractions were incubated with Fe, ADP and NADPH significantly greater amounts of radicals were initially trapped when rats were deficient in vitamin E (whether combined with Se deficiency or not) than from Se-deficient animals or Se- and vitamin E-supplemented controls. After prolonged incubation (ca. 30-45 mins) the free radicals trapped from the microsomes from the Se-deficient animals rose to amounts comparable to those seen in the vitamin E-deficient microsomes. Over the same period of incubation approximately half this quantity of radicals were trapped in liver microsomes from Se- and vitamin E-supplemented rats. The effects of 4-POBN on the levels of peroxidation in the various microsomal fractions were assessed by measuring the thiobarbituric acid reactive substances (TBARS). The presence of 4-POBN significantly reduced the amounts of TBARS formed on incubation and there was a clear distinction between the groups on the basis of the vitamin E status of their diets.