[Lipid peroxidation in rat liver mitochondria in aging and in hyperthyroidism].

The rate of lipid peroxidation (LPO) in rat liver mitochondria induced by the Fe++ + ascorbate system was considerably reduced in 1--12-month-old rats, remained unchanged thereafter up to the 24th postnatal month and was decreased in hyperthyroid rats aged 1- and 3 months. The rate of NADPH-dependent LPO was also sharply decreased up to the 12th month of age, showing a further rise in 24-month-old animals, i. e. thus remained lower than in 1- and 3-month-old rats; under hyperthyroidism the LPO rate was increased in more highly 12-month-old animals. A reverse correlation between the level of reducibility of matrix pyridine nucleotides and the rate of enzymatic LPO in mitochondria was established. A physiological role of LPO is postulated.