LOW FATTY-ACID UNSATURATION PROTECTS AGAINST LIPID-PEROXIDATION IN LIVER-MITOCHONDRIA FROM LONG-LIVED SPECIES - THE PIGEON AND HUMAN CASE

Birds have a much higher maximum longevity (MLSP) than mammals of simi lar metabolic rate. Recent data showed that pigeon mitochondria produc e oxygen radicals at a rate much slower than rat mitochondria, in spit e of showing similar levels of oxygen consumption (Free Rad Res., 21 ( 1994) 317-328). Since oxidative damage from and to mitochondria seems important in relation to aging and longevity, and mitochondrial membra nes are situated at the place where oxygen radicals are generated, we studied protein and lipid peroxidation and fatty acid composition of t he three main membrane phospholipids of liver mitochondria from rats ( MLSP = 4 years) and pigeons (MLSP = 35 years). It was found that pigeo n mitochondria show lower levels of fatty acid unsaturation than rat m itochondria in the three lipid fractions, mainly due to a substitution of highly unsaturated fatty acids (20:4 and 22:6) by linoleic acid (1 8:2), and that these mitochondria are more resistant to lipid peroxida tion. Previous research has also obtained exactly the same major diffe rence in fatty acid composition in human mitochondria when compared to those of rat. Thus, present information suggests that the liver mitoc hondrial membranes of especially long-lived species show both a low le vel of free radical production and a low degree of fatty acid unsatura tion as important constitutive protective traits to slow down aging.